This invention relates to loudspeakers, and, more particularly, to a loudspeaker having a replaceable motor assembly.
Loudspeakers generally comprise a frame, a motor assembly, a voice coil, a diaphragm, a lower suspension or spider and a surround or upper suspension. In one type of speaker, the motor assembly includes a permanent magnet sandwiched between a top plate and a back plate, with a pole piece centrally mounted on the back plate so that both the top plate and magnet are concentrically disposed about the pole piece. A magnetic gap is formed between the pole piece and top plate within which the voice coil is axially movable. Preferably, the voice coil consists of a hollow, cylindrical-shaped former having an inner surface and an outer surface which mounts a winding of wire.
Other types of speakers, known as pot-type speakers, employ a motor assembly having a top plate, a pot structure including a pot wall integrally connected to a back plate and a permanent magnet sandwiched between a top plate and the back plate. A magnetic gap is formed between the pot wall and the top plate within which the voice coil is axially movable.
The voice coil in speakers of the type described above is mounted within the magnetic gap by the upper and lower suspensions and the diaphragm. One end of the diaphragm is connected to the upper suspension, which, in turn, is mounted to the upper end of the frame. The lower suspension is connected at one end to the frame at a point between its upper and lower ends. The free ends of the diaphragm and lower suspension may be mounted to the outer surface of the former of the voice coil and support it for axial movement within the magnetic gap. In many speaker designs, a dust cap is mounted over a central opening formed in the diaphragm so that contaminants are prevented from entering the interior of the speaker.
In the course of operation of speakers of the type described above, electrical energy is supplied to the voice coil causing it to axially move within the magnetic gap. The voice coil, diaphragm, upper suspension, lower suspension, and dust cap, if present, collectively form a “moving assembly” which reciprocates as a unit with the excursion of the voice coil.
The method of fabricating traditional loudspeakers such as noted above involves a process which takes place for the most part within the confines of the frame of the speaker. Initially, the frame is secured by screws, glue or other permanent fasteners to the motor assembly. In one type of speaker, the voice coil is then placed over the pole piece of the motor assembly, and a centering gauge is positioned between the voice coil and pole piece. The gap between the voice coil and pole piece, as well as the height of the voice coil within the overall speaker, are set at this stage of the assembly operation with the centering gauge in place. A similar assembly operation is employed with pot-type speakers to accurately position the voice coil in the magnetic gap between the pot wall and top plate.
After the voice coil is positioned relative to the pole piece or pot wall, the spider or lower suspension is slid along the outer surface of the voice coil, from the top downwardly, until the outer periphery of the lower suspension rests against a spider plateau or seat formed in the frame. When seated, the lower suspension is glued to both the outer surface of the voice coil and to the spider plateau.
Many loudspeaker manufacturers purchase the upper suspension and the diaphragm as a pre-assembled unit from a third party. With the lower suspension in place, the diaphragm of the upper suspension—diaphragm unit is slipped over the voice coil and glued in place on the outer surface of the former. The outer periphery of the upper suspension is then glued to an upper flange of the frame, and a gasket is attached to such upper flange outside of the upper suspension. Once all the glue has cured, the voice coil gauge is removed from between the voice coil and pole piece by pulling it upwardly through the central opening formed in the diaphragm. A dust cap is then glued to the diaphragm over its central opening.
Beginning with the pole piece or pot wall of the motor structure, essentially the entire speaker consists of elements which are intended to be oriented in concentric relation to one another. The voice coil is concentric to the pole piece or pot wall, and the upper suspension, lower suspension and diaphragm are concentric to the voice coil. Each of these elements is made within certain tolerances, and the tolerance “stack-up” or combined total from the voice coil radially outwardly to the upper suspension can be significant. Further, no effort is typically made to obtain fine alignment between the frame and motor assembly which can add to tolerance stack-up problems, i.e., the seat or spider plateau in the frame where one end of the lower suspension is mounted, and the upper flange of the frame where the upper suspension is mounted, can be out of concentricity with respect to the pole piece or pot wall of the motor structure. In most speaker designs, the total concentric tolerance stack-up must be absorbed by the upper suspension. Especially during high excursion of the voice coil, the upper suspension can deform if the tolerance stack-up is too high, causing the voice coil to “rock” or pivot within the magnetic gap. This can severely degrade the performance of the speaker.
Another problem with prior loudspeakers and their method of manufacture involves repairs and warranty work. As noted above, many of the speaker elements are permanently attached together with glue. In the event of a failure of a speaker element, a great deal of time and effort must be expended to clean the surfaces where glue has been applied before a new part can be installed. Often, it is less expensive and time consuming to simply replace entire portions of the speaker, including the entirety of the motor assembly, rather than to attempt to repair a failed part.
The loudspeaker of this invention provides for precise alignment between the frame and motor assembly so that the voice coil is properly positioned both in the radial and vertical directions with respect to the magnetic gap, while permitting the frame and motor assembly to be easily and quickly separated from one another to facilitate the performance of warranty work, other repairs and/or the replacement of the motor assembly in its entirety.
The loudspeaker of this invention is preferably a pot-type speaker having a frame with a voice coil, and a motor assembly. The motor assembly of the speaker includes a pot structure comprising a vertically extending pot wall integrally formed with a back plate, which is oriented generally parallel to a top plate, with a permanent magnet located between the back plate and the top plate. A magnetic gap is formed between the pot wall and top plate within which the voice coil is axially movable.
In one presently preferred group of embodiments of this invention, the lower end of the frame is formed with a seat having a radial alignment surface and a vertical alignment surface. Similarly, the pot structure is formed with both radial and vertical alignment surfaces. In these embodiments, an element such as a flange or plate protrudes radially outwardly from the pot structure. The upper surface of the flange forms the vertical alignment surface of the pot structure, and the radial alignment surface may be the outer edge of the flange or the exterior surface of the pot wall. When the frame is placed into engagement with the motor assembly, the vertical alignment surface of the frame contacts the upper surface of the flange or plate, and the radial alignment surface of the frame engages the exterior surface of the pot wall or the outer edge of the flange. These aligning surfaces of the frame and pot structure ensure that the voice coil coupled to the frame is accurately positioned, both in a vertical and radial direction, within the magnetic gap of the motor assembly. Fasteners connect the motor assembly to the frame.
In another group of preferred embodiments of this invention, the desired radial alignment of the voice coil within the magnetic gap of the motor assembly is achieved by the engagement between a radial alignment surface formed on the lower end of the frame and the exterior surface of the pot wall of the motor assembly. In order to ensure that the voice coil is properly vertically aligned within the magnetic gap, the pot structure is formed with notches which receive projections extending from the lower end of the frame when the frame is fitted over the motor assembly. The projections can take the form of set screws or flexible arms carried by the lower end of the frame. When each projection is seated within a corresponding notch in the pot structure, the voice coil is in the appropriate vertical relationship with respect to the magnetic gap.
A still further embodiment of this invention employs a flange extending radially outwardly from the pot structure. The flange has an upper surface and a number of circumferentially spaced holes. The lower end of the frame includes a vertical alignment surface, and a number of circumferentially spaced pins. When the frame is fitted onto the motor assembly, the pins are received within the holes in the flange to provide radial alignment of the voice coil with respect to the magnetic gap. The vertical alignment surface of the frame rests atop the upper surface of the flange to accurately vertically locate the voice coil in the magnetic gap.
The structure, operation and advantages of the presently preferred embodiment of this invention will become further apparent upon consideration of the following description, taken in conjunction with the accompanying drawings, wherein:
Referring now to the drawings, a number of alternative embodiments of a pot-type loudspeaker 10 are illustrated which have a substantial amount of common structure but variations of how the frame 12 of the speaker 10 and its motor assembly 14 may be mounted together so as to permit quick and easy separation of the frame 12 and motor assembly 14 from one another while ensuring that accurate alignment between the two is obtained upon assembly. The common elements of the speaker 10 are initially, described below, followed by a discussion of distinct embodiments of the alignment structure.
Common Speaker Elements
With reference initially to
The motor assembly 14 comprises a top plate 32, a pot structure 34 and a permanent magnet 36. The pot structure 34 consists of a vertically extending pot wall 38 which connected to or integrally formed with a back plate 40. The top plate 32 and back plate 40 are oriented generally parallel to one another with the magnet 36 located between them. A magnetic gap 42 is formed in the space between the pot wall 38 and top plate 32 within which the voice coil 30 is axially movable. In order for the speaker 10 to operate properly, the voice coil 30 must be accurately aligned within the magnetic gap 42 both radially and vertically. The terms “radial” and “radially” used herein in discussing alignment of the voice coil 30 or the location of different elements of the speaker 10 refer to a direction radially outwardly from the center of the speaker 10, i.e. generally coincident with the center of the bore 44 in the magnet 36. The discussion which follows is directed to the structure of the various embodiments of the speaker 10 of this invention for achieving accurate radial and vertical alignment of the voice coil 30 within the magnetic gap 42, while allowing the motor assembly 14 and frame 12 to be readily separated from one another.
Embodiments of
Although somewhat different from one another, the embodiments of this invention shown in
Referring initially to
In order to assemble the speaker 10 depicted in
An alternative embodiment of this invention is shown in
A similar concept to that described in connection with a discussion of
Referring now to
Embodiments of
Referring now to
In the specific embodiment of
The embodiment of this invention illustrated in
As shown in
Embodiment of
Referring now to
While the invention has been described with reference to a preferred embodiment, it should be understood by those skilled in the art that various changes may be made and equivalents substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof.
For example, in the embodiment of
In still further embodiments of this invention, the motor mounting plate 80, annular ring and/or arc segments described above in connection with a discussion of alternative embodiments of
Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
The present application is a divisional of co-pending U.S. application Ser. No. 11/847,448 filed on Aug. 30, 2007, which is incorporated herein by reference in its entirety to form a part of the present disclosure.
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Number | Date | Country |
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Number | Date | Country | |
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20110299717 A1 | Dec 2011 | US |
Number | Date | Country | |
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Parent | 11847448 | Aug 2007 | US |
Child | 13204833 | US |