Acoustics – Sound-modifying means – Housing or enclosure
Reexamination Certificate
2000-03-02
2003-07-29
Dang, Khanh (Department: 2837)
Acoustics
Sound-modifying means
Housing or enclosure
C181S153000, C181S151000
Reexamination Certificate
active
06598700
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to loudspeaker cabinets composed of a moldable wood material and a method for making the same. In particular, the present invention relates to loudspeaker cabinets composed of a compression molded cellulose (CMC) material resulting in a cabinet for loudspeakers with improved acoustic and physical properties.
BACKGROUND OF THE INVENTION
The quality of sound created by a loudspeaker is significantly influenced by the shape of the cabinet in which it is mounted and by the acoustic properties of the material from which the cabinet is made.
Loudspeaker cabinets are traditionally constructed of various types of wood or fabricated wood materials such as particle-board, press board, plywood, and fiberboard that are available only in sheet form. Cabinets fabricated from sheets of material possess angular junctions and flat internal surfaces that degrade the accuracy of the sound generated by the loudspeaker. Flat internal cabinet surfaces reflect sound waves in a regular pattern that interfere with the waves emanating from the loudspeaker. This interference creates standing wave cancellation resulting in distortion and loss of loudspeaker efficiency. The quality of reproduced sound from traditional “box” shaped loudspeaker cabinets is inferior to the quality of reproduced sound from loudspeaker cabinets incorporating curved internal surfaces. Curved internal cabinet surfaces reflect sound waves randomly thereby minimizing standing wave cancellation and distortion and enhancing efficiency.
Additionally, the leakage of air at the connection points of flat panels adversely affects the loudspeaker's overall performance. Molded cabinet construction eliminates joints thereby ensuring a leak-proof cabinet.
Traditional cabinet materials are available only in fixed densities as they are generally intended for architectural and/or structural applications. The densities are not always ideal for acoustic applications since the rate of decay of the sound energy in the material directly affects the quality of the sound produced by the loudspeaker incorporated into cabinets composed of these materials. In contrast, the density of compression molded cellulose (CMC), the present invention, can be controlled and modified by formulation and process variations to conform to specific acoustic criteria. This flexibility greatly enhances the quality of the sound from the loudspeaker mounted in the CMC cabinet.
There is a need in the industry for loudspeaker cabinets, and a material and process for making the same, with improved acoustic and physical properties. There is also a need in the industry, especially the automotive, marine, and other applications, for a loudspeaker cabinet and material with a greater resistance to water, weather, and abrasion damage. There is also a need in the industry for a moldable material with improved physical properties such as abrasion and water resistance for use in non-loudspeaker applications.
Currently available loudspeaker cabinets are also limited in the designs available with regard to shape and surface detail due to the materials employed. Plastic or non-cellulose based materials may be available, but are not readily capable of accepting paint or other decorative treatments, may be difficult to work with, and the costs of production may be prohibitively high.
In many applications, loudspeaker performance is enchanced if the cabinet can be made airtight. Cabinet construction using traditional materials with angular joints makes airtight cabinet construction nearly impossible. There is a need in the industry to provide cabinets that are airtight.
There is also a need in the industry to provide loudspeaker cabinets with various densities to match the requirements of the loudspeaker. There is also a need in the industry to be able to manufacture cabinets with the above advantages from readily available materials with predictable costs. There is also a need in the industry to provide loudspeaker cabinets with an increased service life which are not susceptible to rot or other types of decay or degradation. There is also a need in the industry for a material which is capable of being manipulated (cut, drilled, threaded, sanded, etc.) easily with standard tools and techniques. There is also a need in the industry to provide loudspeaker cabinets which are not only impermeable to water and other liquids, but also to gases and other fumes which may be harmful to the loudspeaker components. There is also a need in the industry to provide loudspeaker cabinets not only with varying material densities, but also with controllable and variable wall thickness.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets having improved acoustic properties.
It is another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets having improved physical properties.
It is a further object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets having unlimited design latitude with regard to shape and surface detail.
It is still another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets having high resistance to water and weather and abrasion damage.
It is yet another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets capable of accepting paint and or other decorative treatments.
It is still yet another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets having a lower per unit fabricated cost.
It is another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets having the ability to be produced by simple methods such as low-pressure compression molding using fabricated tooling.
It is another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets having few or no seams or joints ensuring an air-tight enclosure.
It is another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets of varying material densities to meet the specific requirements of various acoustic applications.
It is another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets from readily attainable materials with predictable costs.
It is another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets with long service life capability.
It is another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets with the capability of being manipulated with standard tools and techniques.
It is another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets that are impermeable to water and air.
It is another object of the present invention to provide a material and process with which to fabricate loudspeaker cabinets that are of controllable and uniform wall thickness.
Additional objects and advantages of the invention are set forth, in part, in the description which follows and, in part, will be apparent to one of ordinary skill in the art from the description and/or from the practice of the invention.
SUMMARY OF THE INVENTION
In response to the foregoing challenge, Applicants have developed an innovative, economical material and process yielding weatherproof cabinets of any shape, which have greater acoustic integrity and improved physical properties at a lower cost per unit. The material, compression molded cellulose (CMC) is a novel blend of wood fibers and other organic and inorganic fillers bonded within a matrix of thermoset resins.
In accordance with the present invention, a process for the mixing, extrusion, and compression
Collier Shannon Scott PLLC
Coulby John N.
Dang Khanh
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