Patent Application
20180324528
This invention relates to loudspeakers, and, more particularly, to a loudspeaker having a field replaceable moving assembly and a method of assembling the loudspeaker.
Loudspeakers generally comprise a frame, a motor structure, a diaphragm, a lower suspension or spider and a surround or upper suspension. In one type of speaker, the motor structure includes a permanent magnet sandwiched between a top plate and a back plate, with a pole piece having a through bore 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 a 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.
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 are 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.
Another common type of speaker, known as a “pot” speaker, is similar to that described above except the back plate is integrally formed with a pot wall which is concentrically disposed about a top plate and a magnet formed with aligning through bores. No pole piece is provided, but instead, the magnetic gap is formed by a radial space between the pot wall and top plate. Otherwise, pot speakers are constructed and operate in essentially the same manner as the speaker described above.
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 structure. The voice coil is then placed over the pole piece of the motor structure, 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.
After the voice coil is positioned relative to the pole piece, 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 former 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 pre-assembled upper suspension—diaphragm unit is slipped over the voice coil and glued in placed 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 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, 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 structure 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 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. Generally, it requires skilled workers with special tools to clean part surfaces of glue, apply new glue and assemble new parts within concentricity tolerances. Moreover, expensive, specialized glues are employed in the manufacture of loudspeakers which are not available to the public. Repairs and warranty work on loudspeakers are therefore typically performed at the factory by skilled workers rather than in the field.
The loudspeaker and method of assembly of this invention is predicated on the concept of simplifying the repair or replacement of elements of a loudspeaker by employing a method of assembly, and a loudspeaker construction, in which the moving assembly of the speaker can be removed and replaced as a unit in the field by an unskilled worker without the use of special tools and without special knowledge of speaker repair. The voice coil, upper suspension, lower suspension and diaphragm comprise the “moving assembly,” which, as described below, is formed as a unit outside of the speaker frame. The moving assembly is connected to a separately assembled frame and motor structure using a centering tee having a head section connected to the lower suspension and a stem section insertable within a central opening of the motor structure formed by aligning through bores in the top plate and the pole piece or magnet.
In the event of a failure of one of the elements of the moving assembly, which is typically where a problem arises, the entire moving assembly may be disconnected from the motor structure, and removed. A new moving assembly, fabricated at a factory and shipped as a unit to a retailer or off-site repair center, may be mounted to the motor structure in the field. As noted above, and described below, the centering tee and the central opening in the motor structure, allow for precise alignment of all speaker elements when the moving assembly is replaced without using gauges, guides, fixtures or other special equipment. Additionally, no dust cap is required with the speaker of this invention because the diaphragm may be formed without a central opening.
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 to the Figs., the speaker 10 of this invention comprises a frame 12, a motor structure 14 and a moving assembly 16 including a centering tee 18. Throughout the following description, the terms “top,” “bottom,” “upper” and “lower” are meant to refer to directions and/or locations with the speaker 10 in the orientation shown in the Figs. The terms “inner” and “outer” refer to a radial relationship of parts or structure beginning at the longitudinal axis of the speaker 10 which, for purposes of this discussion, is considered to pass through a central opening in the motor structure 14, as described below.
The frame 12 has an upper flange 20 formed with a number of spaced, surround locator holes 22 and a number of spaced, clamp bores 24 in between groups of locator holes 22 as shown. The lower portion of the frame 12 is formed with a lower flange 26 having spaced locator holes which receive screws 28.
The speaker 10 depicted in the drawings is a “pot” type speaker in which the motor structure 14 includes a pot wall 30 concentrically disposed about a permanent magnet 32 and a top plate 34. The pot wall 30 is integrally formed with a back plate 36 upon which the magnet 32 is mounted. As shown in
It should be understood that while a pot type speaker 10 is illustrated in the drawings this invention is equally applicable to speakers having motor structures of the type shown, for example, in U.S. Pat. No. 6,496,590, the disclosure of which is incorporated by reference in its entirety herein. As noted above, the motor structure of these types of speakers includes a top plate and a magnet concentrically disposed about a pole piece which is integrally formed with a back plate. The central opening in such motor structure comprises a through bore formed in the pole piece.
The frame 12 and motor structure 14 of the speaker 10 are illustrated in
As best seen in
In one preferred embodiment, an adaptor 62 is affixed to the upper end of the former 54. The adaptor 62 is a cylindrical-shaped member having an upwardly facing glue well 64 and a downwardly facing glue well 66. The inner edge of the lower suspension 48 is adhesively mounted within the downwardly facing glue well 66 of the adaptor 62 so that the lower suspension 48 is located within the hollow interior 56 of the former 54 of voice coil 46. The lower end of the diaphragm 52 is preferably formed with a foot 68 which is received and adhesively mounted within the upwardly facing glue well 64. The opposite end of the diaphragm 52 is mounted to the surround 50. As shown in the Figs., the surround 50 is integrally formed with an annular ring 65 having a downwardly facing, circumferentially extending recess 67.
The moving assembly 16 further comprises centering tee 18 which is formed with a head section 70 and a stem section 72. The head section 70 is affixed to the lower suspension 48. The stem section 72 has an upper portion 74, a smaller diameter lower portion 76 and an intermediate portion 75 located between the upper and lower portions 74, 76. A shoulder 78 is formed at the juncture of the upper portion 74 and intermediate portion 75, and at least part of the lower portion 74 is formed with external threads 80. A through bore 81 is formed in the centering tee 18 which extends along its entire length, e.g. through the head section 70 and stem section 72.
The moving assembly 16 including centering tee 18 is depicted in
Referring now to
The moving assembly 16 is mounted to the frame 12 by a surround ring 84 formed with a number of internally threaded bores 86. As seen in
It should be understood that the structure for mounting the surround 50 to the frame 12 shown in the Figs. is one presently preferred embodiment of this invention. It is contemplated that the construction taught in U.S. Pat. No. 5,949,898 for connecting the frame 12 and surround 50 could be employed in the speaker 10 of this invention, and the disclosure of such patent is hereby incorporated by reference in its entirety here.
The dimensions of stem section 72 of the centering tee 18 are precisely manufactured to ensure the moving assembly 16 is mounted in concentric relation to the motor structure 14. In particular, the diameter of the intermediate portion 75 of the stem section 72 snugly fits within the through bore 42 in the top plate 34 of motor structure 14. Further, the shoulder 78 formed between the upper and intermediate portions 74, 75 of stem section 72 engages top plate 34 so that the stem section 72 is located at the desired position within the motor structure 14 to receive the nut 82.
As noted above, one important aspect of this invention is the simplification and reduction in the cost of repairs and warranty work it provides. Prior to this invention, in the event of a failure of a speaker element a great deal of time and effort had to be expended to clean the surfaces where glue had been applied before a new part could be installed. That process typically requires skilled workers with special tools to clean part surfaces of glue, apply new glue and assemble new parts within concentricity tolerances using gauges, guides, fixtures or other special equipment. In most instances, such process would needed to be performed at the factory by skilled workers rather than in the field.
In the loudspeaker 10 and method of assembly of this invention, failure of any one of the elements of the moving assembly 16, which is typically where a problem arises, can be overcome by disconnecting the entire moving assembly 16 from the motor structure 14. This is accomplished by removing the nut 82 from the stem section 72 of the centering tee 18, removing the screws 90 from the surround ring 84 and upper flange 20, and then lifting the entire moving assembly 16 out of the motor structure 14. A new moving assembly 16, fabricated at a factory and shipped as a unit to a retailer or off-site repair center, may then mounted to the motor structure 14 in the field as described below. Such a repair can be accomplished by an unskilled worker without the use of gauges, guides, fixtures or other special equipment.
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 may be 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, while an adaptor 62 is illustrated in the Figs. for connecting the lower suspension 48 and diaphragm 52 to the former 54 of voice coil 46, other mounting arrangements may be used including affixing such components directly to the former 54.
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.
