Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Electromagnetic
Reexamination Certificate
2001-07-31
2004-10-05
Le, Huyen (Department: 2643)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Electromagnetic
C381S403000, C381S407000, C381S430000, C181S171000
Reexamination Certificate
active
06801634
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a loudspeaker coil suspension and dome system that acts to protect the coil from electrical shorting.
2. Related Art
A loudspeaker is a device for converting variations of electric energy into corresponding variations of acoustic energy. To convert the electrical energy into sound, a combination of a diaphragm and a compression driver is coupled to the throat of a horn. The compression driver typically includes a phasing plug made of ferromagnetic material having a plurality of bores between the rear side and the front side of the phasing plug.
Generally, the coil is wrapped around the exterior side of a cylindrically shaped former. The combination of the former and coil are then disposed within an annular magnetic gap enabling free vibration in a direction along the longitudinal axis of the former. The vibration causes a corresponding vibration of the diaphragm generating sound. The suspension needs to flexible in order to accommodate the excursion of the cone or diaphragm. At the same time, the suspension needs to keep the cone or diaphragm from tipping or becoming “de-centered.”
To suspend the diaphragm adjacent to the rear side of the compression driver, the outer perimeter of the diaphragm is coupled to a suspension, which in turn is attached to a mounting plate. With the configurations that have been used in the past, the outer surface of the voice coil is substantially exposed and not insulated.
To generate sound, a static magnetic field, usually produced by a permanent magnet, is applied so that an alternating signal current flowing through the voice coil causes it to vibrate along its cylindrical axis. This in turn causes the diaphragm to vibrate along the axis of the plurality of bores and generate sound waves corresponding to the signal current. The sound waves are directed through the bores toward the front side, which then radiates the sound waves into the air through the horn.
Despite best manufacturing efforts, speakers may fail due to excessive mechanical and thermal stresses. For example, suspensions can fail due to environmental factors such as exposure to heat, UV rays or humidity. Adhesives attaching the suspension to the diaphragm can also fail if applied improperly or if excess mechanical stress is applied to the jointing area. Likewise, adhesives attaching the former to the diaphragm can fail. This happens because applying adhesive between the suspension and the diaphragm, and between the former and the diaphragm, can be a delicate process and possibly misapplied. Another way the loudspeaker might fail is due to over heating of the voice coil. If the voice coil experiences excessive heat expansion, it may come into contact with the sidewalls of the magnetic gap. If this condition occurs and the voice coil is not insulated, the resulting contact between the voice coil and the sidewalls can cause an electrical short circuit and terminal failure will occur.
Another shortcoming of current compression driver devices is that additional acoustic energy may not be provided in high frequency applications. In high frequency applications, additional acoustic energy is desired from the compression driver, but with current designs such additional acoustic energy may not be provided. Therefore, there is a need for a compression driver that can generate additional acoustic energy at high frequency application, a coil and suspension assembly system whose manufacturing process is simplified and a system for protecting the voice coil from experiencing electrical short circuits.
SUMMARY
This invention provides an assembly system for a voice coil, suspension, and diaphragm. In one embodiment of the invention, a continuous layer of high temperature resistant polymer is shaped to form a suspension, a pocket adapted to receive the voice coil and a flange adapted to couple to the diaphragm. A continuous layer of polymer may be shaped to perform several functions, such as the suspension, the former, and an attachment to the diaphragm. The coil may be inserted inside the pocket to protect the voice coil from electrical shorting as the voice coil expands or shrinks. The assembly system may also allow for the manufacture of different products via simply changing the diaphragm material. The diaphragm can then be optimized for different uses by changing materials. This may provide manufacturing flexibility by allowing various products to be assembled by the same tooling.
This invention may also allow utilization of an inner flange area of a suspension to act as a spring allowing the generation of additional acoustic energy from the compression driver. The inner flange area may be tuned to vibrate at a predetermined high frequency thus adding additional acoustic energy to the diaphragm motion. In certain applications where more acoustic energy is desired, the inner flange area may be tuned to provide that extra acoustic energy.
To further increase the high frequency energy generated by the compression driver, the diaphragm may be coupled to the bottom side of the inner flange area. Such an arrangement places the diaphragm closer to the phasing plug minimizing the space or cavity between the two items. With a smaller cavity, the resonance in the cavity increases, resulting in an increase in the high frequency energy generated by the compression driver.
Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims.
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Harman International Industries, Inc.
Le Huyen
Squire Sanders & Dempsey LLP
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