Abstract:
This invention is directed to a loudspeaker having a lead wire management system including guides located at both the voice coil and the frame of the speaker. Each guide is angled allowing them to control the arc at which the lead wires extend between the voice coil and frame, and rounded edges of the guides relieve stress on the lead wire joint connections during motion of the voice coil.

Description:
FIELD OF THE INVENTION 
   This invention relates to loudspeakers, and, more particularly, to a loudspeaker lead wire management system in which the lead wires connected between the voice coil and frame are relatively easy to install and of the proper length and arc to avoid stress on their joint connections and to prevent contact with the diaphragm, spider and other elements during speaker operation. 
   BACKGROUND OF THE INVENTION 
   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 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. The voice coil consists of a hollow, cylindrical-shaped former including an inner surface and an outer surface which mounts a winding of wire having a voice coil lead. Lead wires are connected at one end to the voice coil lead of the wire winding, and at their other end to electrical terminals which are fixed to the frame. The voice coil 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 or spider is connected at one end to a seat or spider plateau formed in the frame. The free ends of the diaphragm and spider are mounted to the outer surface of the former of the voice coil and support it for axial movement within the magnetic gap. In the course of operation, electrical energy is supplied via the lead wires to the voice coil causing it to axially move within the magnetic gap. The voice coil, diaphragm, upper suspension and spider collectively form a “moving assembly” which reciprocates as a unit with the excursion of the voice coil. 
   Loudspeakers of the type described above are typically manufactured as follows. The motor structure is assembled by gluing the magnet in between the top plate and back plate, and then the frame and motor structure are connected together. Using precision shim stock positioned between the voice coil former and pole piece, the voice coil is located within the motor structure at the appropriate height. In most instances, one end of each lead wire is attached to the voice coil lead of the wire winding of the voice coil before it is placed in position relative to the pole piece. 
   As noted above, the voice coil is suspended within the magnetic gap of the motor structure by the upper suspension or surround and the spider. First, the inner diameter of the spider is slid down over the former of the voice coil to a height which allows its outer diameter to lay flat on the spider plateau formed in the frame. The inner diameter of the spider is then glued to the voice coil former and its outer diameter is glued to the spider plateau. With the spider in position, the body of the diaphragm is slid over the voice coil former. In most instances, the diaphragm and surround are supplied by the manufacturer as a single, interconnected unit. Typically, a foot or flange of the diaphragm rests on the joint connection between the spider and the voice coil so that the diaphragm is placed at the appropriate height relative to the voice coil. The diaphragm is glued to the voice coil, and the surround is glued to a flange at the top of the frame. The lead wires are then threaded through holes in the diaphragm and extended toward the frame. A dust cap is often attached to the diaphragm, over its open center, to prevent dust and other debris from entering the voice coil or motor structure. Finally, the free end of each lead wire is attached to the electrical terminals on the frame, which are usually attached to the frame in a prior assembly operation. 
   Once the voice coil is positioned on the pole piece of the motor structure, all other assembly operations noted above must be performed within the loudspeaker frame because fixtures are employed to obtain proper alignment of the remaining parts. Depending upon the physical size of the loudspeaker being assembled, it is difficult to fit one&#39;s hands into the loudspeaker frame to work. Although many frames are formed with openings or “windows,” these openings are usually of limited size particularly in small speakers. This constraint can make installing the lead wires a real challenge, and it is extremely difficult to accurately gauge the length of the lead wires within the frame. 
   Several problems arise if the lead wires are not properly installed in a speaker. If a lead wire is too short, it can be drawn too tight during high excursions of the voice coil risking damage to the moving assembly and the lead wire connections. On the other hand, lead wires which are too long create a large arc between the voice coil and electrical connections at the frame. Long lead wires can dynamically misbehave during diaphragm movement, potentially contacting the diaphragm or spider, and create undesirable noise. Further, not unlike a guitar string, the suspended length of the lead wire can have its own resonance behavior. Consequently, if the length of the lead wire is not carefully considered during the design phase of the speaker and then properly installed, a loudspeaker can be rendered nearly useless by the undesirable noises created. 
   There have been attempts in the prior art to manage the dynamic behavior of speaker lead wires. At the frame, lead wires are very often soldered to electrical terminals with a small amount of flexible glue being applied at the location where the lead wire leaves the terminal. The purpose of the flexible glue is to attempt to control the angle at which the lead wire exits the terminal, to provide at least some motion damping and to relieve stress at the connection of the lead wire to the terminal. At the other end of the lead wires, flexible glue is typically used where the lead wires extend through holes in the diaphragm in an attempt to control the angle of the lead wire at that location and also to assist with management of the dynamic behavior of the lead wire, including stress relief at the lead wire connection to the voice coil. Unfortunately, applying flexible glue consistently at either end of the lead wires is very difficult since these operations must be performed by hand within the interior of the speaker frame. 
   SUMMARY OF THE INVENTION 
   This invention is directed to a loudspeaker having a lead wire management system including guides located at both the voice coil and the frame of the speaker. Each guide is angled allowing them to control the arc at which the lead wires extend between the voice coil and frame, and rounded edges of the guides relieve stress on the lead wire connections during motion of the voice coil. 
   In one presently preferred embodiment, a voice coil bracket is mounted to the voice coil having an integral guide in the form of a bore which is angled in a direction toward the frame and has a smooth outlet edge. A frame bracket is mounted to the frame and it is formed with the same guide construction as the voice coil bracket except with one or more bores angled toward the voice coil. The guide in each bracket receives and supports one lead wire which is connected at one end to the voice coil lead and at the opposite end to an electrical connector secured to the frame. The angles of the guides in the two brackets are chosen to control the arc at which the lead wires extend between the voice coil and frame. The arc of the lead wires must be such that they do not contact the diaphragm, or the spider, during excursion of the voice coil. The brackets employed in this invention provide for precise control of the lead wire arc and length which ensures that the dynamic behavior of the lead wires is properly managed. Additionally, the smooth outlet edge of the bores forming the guides in each bracket is effective to reduce stress or pulling on the lead wire connections particularly during high excursions of the voice coil. 
   The voice coil bracket and frame bracket of this invention eliminate the need for flexible glue used in the prior art to attempt to manage the dynamic behavior of the lead wire, and allows the lead wires to be mounted to the voice coil outside of the frame. Unlike the prior art, the lead wires need not be threaded through holes in the diaphragm during assembly of the speaker which simplifies the manufacturing process. 
   In some embodiments of this invention, the voice coil bracket is formed with an upper seat to receive and mount the lower end of the diaphragm, and a lower seat which mounts the inner diameter of the spider. Alternatively, the diaphragm and/or the spider may be mounted directly to the voice coil. Using fixtures to obtain proper alignment and vertical spacing, either construction allows the spider to be mounted to the voice coil bracket and to the frame bracket outside of the frame. Preferably, the lead wires are attached to the wire winding and voice coil bracket at one end, and to the frame bracket at the opposite end, outside of the frame as well. The spider, voice coil and frame bracket are inserted into the speaker frame as a unit by sliding the voice coil over the pole piece of the motor structure, and then gluing the foot of the frame bracket to a plateau formed in the frame. The end of the lead wires carried by the frame bracket may then be connected to electrical terminals mounted to the frame or integrated with the frame bracket. 

   
     DESCRIPTION OF THE DRAWINGS 
     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: 
       FIG. 1  is a cross sectional view of a prior art loudspeaker which includes holes formed in the diaphragm to receive lead wires which are then mounted to an electrical connector on the speaker frame; 
       FIG. 2  is an enlarged view of the encircled portion of  FIG. 1  showing a lead wire extending through the diaphragm; 
       FIG. 3  is an isometric cross section of the speaker shown in  FIG. 1 ; 
       FIG. 4  is a view similar to  FIG. 1  but depicting a speaker having the voice coil bracket and frame bracket of this invention with the lead wires connected below the voice coil bracket; 
       FIG. 5  is an enlarged view of the encircled portion of  FIG. 4 ; 
       FIG. 6  is an isometric cross section of the spider subassembly shown in  FIG. 4  illustrating the frame bracket in more detail; 
       FIG. 7  is a view similar to  FIG. 4  except with the lead wire mounted to the voice coil at a location above the guide in the voice coil bracket; 
       FIG. 8  is an enlarged view of the encircled portion of  FIG. 7 ; 
       FIG. 9  is an isometric cross section of the spider subassembly shown in  FIG. 7 ; 
       FIG. 10  is a view similar to  FIG. 7  except with the diaphragm mounted directly to the voice coil instead of to an upper seat formed in the voice coil bracket; 
       FIG. 11  is an enlarged view of the encircled portion of  FIG. 10 ; 
       FIG. 12  is a view similar to  FIG. 4  except with the diaphragm mounted directly to the voice coil instead of to a seat formed in the voice coil bracket; 
       FIG. 13  is an enlarged view of the encircled portion of  FIG. 12 ; 
       FIG. 14  is a cross sectional view of a loudspeaker depicting the voice coil bracket and frame bracket of this invention with both the diaphragm and the spider mounted directly to the voice coil; 
       FIG. 15  is an enlarged view of one encircled portion of  FIG. 14  showing the voice coil bracket; 
       FIG. 16  is an enlarged view of another encircled portion of  FIG. 14  illustrating the frame bracket; 
       FIG. 17  is an isometric cross section of the speaker of  FIG. 14 ; 
       FIG. 18  is a cross sectional view of a loudspeaker depicting the voice coil bracket and frame bracket of this invention with both the diaphragm and the spider mounted directly to the voice coil; 
       FIG. 19  is an enlarged view of one encircled portion of  FIG. 18  showing the voice coil bracket; 
       FIG. 20  is an enlarged view of another encircled portion of  FIG. 18  illustration the frame bracket; and 
       FIG. 21  is an isometric cross section of the speaker of  FIG. 18 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring initially to  FIGS. 1 through 3 , a loudspeaker  10  is illustrated which includes a standard, prior art connection of the lead wires to the voice coil and frame, as described below. The speaker  10  generally comprises a motor structure  12 , a frame  14  mounted to the motor structure  12 , a diaphragm  16 , a lower suspension or spider  18  and an upper suspension or surround  20 . Conventionally, the motor structure  12  includes a top plate  22  and a back plate  24  which are spaced from one another and mount a pair of permanent magnets  26  and  27  between them. A pole piece  28  is integrally formed with and extends upwardly from the back plate  24  into a central bore  30  formed in both magnets  26 ,  27  and the top plate  22 . A magnetic gap  32  is formed between the top plate  22  and the pole piece  28 . A voice coil  34  is also provided which includes a hollow, cylindrical-shaped former  36  having an inner surface  38  and an outer surface  40  which mounts a wire winding  42 . The former  36  is concentrically disposed about the pole piece  28 , and the voice coil  34  is axially movable within the magnetic gap  32  during operation of the speaker  10 . 
   The voice coil  34  is held in place with respect to the pole piece  28  by the diaphragm  16 , spider  18  and surround  20 . In the prior art speaker  10  shown in  FIGS. 1-3 , the inner diameter of the diaphragm  16  is affixed to the former  36  by adhesive or the like, and its outer diameter connects to the surround  20 . The surround  20 , in turn, is mounted to the upper end  44  of the frame  14  as shown. The spider  18  is connected to the outer surface  40  of the former  36  along its inner diameter, and a foot  46  formed at the outer diameter of the spider  18  is glued directly to a seat or spider plateau  48  formed in the frame  14 . 
   A dust cap  50  is mounted to the diaphragm  16  in position to overlie the voice coil  34  and pole piece  28  in order to protect such elements from dirt, dust and other contaminants. A dust cap cavity is therefore formed in the area defined by the lower portion of the diaphragm  16 , the dust cap  50 , the voice coil  34  and the pole piece  28 . 
   As noted above, each lead wire  52  of the speaker  10  is mounted at one end to the wire winding  42  and at the other end to an electrical terminal  51  connected to the frame  14 . Each lead wire  52  is extended through a bore  53  formed in the diaphragm  16 . In response to the input of electrical energy to the wire winding  42 , the voice coil  34  is moved axially with respect to the fixed motor structure  12 . Because the diaphragm  16 , spider  18 , surround  20  and dust cap  50  are operatively connected to the voice coil  32 , such elements also move with the excursion of the voice coil  32  thus collectively forming a moving assembly. 
   Referring now to  FIGS. 4 through 21 , the loudspeaker  10  is depicted with alternative embodiments of a novel means of mounting lead wires  52  to the voice coil  34  and to the frame  14  according to this invention. Each embodiment is described separately below with reference to specific Figs., it being understood that structure of the loudspeaker  10  common to each embodiment, and to the prior art speaker shown in  FIGS. 1 to 3 , is given the same reference numbers throughout. For purposes of the present discussion, the terms “upper,” “lower,” “above,” “below,” “top” and “bottom” refer to spatial orientations with the speaker  10  positioned as it is shown in the Figs. 
   In the embodiment of  FIGS. 4 through 6 , a voice coil bracket  54  is provided which is formed with a flange  56  shaped to rest against the outer surface  40  of the voice coil former  36 . A frame bracket  58  is also provided, having a foot  60  mounted to a plateau  62  formed in the frame  14 , or, alternatively, integrally formed with the frame  14 . Although only one voice coil bracket  54  and one frame bracket  58  are shown in  FIGS. 4-6 , it should be understood that there is one voice coil bracket  54  and one frame bracket  58  for each of the typically two lead wires  52  employed in most speakers. Alternatively, each of the voice coil bracket  54  and frame bracket  58  could be formed as a single unit with two guides having the same configuration described below. 
   The voice coil bracket  54  includes a guide  64  in the form of a bore having an inlet end  68  and an outlet end  70  with a smooth, generally rounded edge. The guide  64  is angled toward the frame bracket  58 , for purposes to become apparent below. An upper seat  74  is formed in the voice coil bracket  54  adjacent to the flange  56 , and a lower seat  76  is formed at the base of the voice coil bracket  54  near the inlet end  68  of the guide  64 . Using appropriate fixtures (not shown), the lower end of the diaphragm  16  is glued within the upper seat  74 , and the inner diameter of the spider  18  is glued to the lower seat  76 . Additionally, the flange  56  of the voice coil bracket  54  is glued to the former  36  at a location, in this embodiment, which is above the voice coil lead  78  extending from the wire winding  42 . 
   The frame bracket  58  is formed with a guide  80  at its upper end in the form of a bore having a rounded inlet end  82  and an outlet end  84 . The guide  80  is angled in a direction toward the voice coil bracket  54 . A seat  86  is formed in the frame bracket  58 , between the guide  80  and foot  60 , which receives and mounts the outer diameter of the spider  18 . 
   To simplify and speed up the speaker manufacturing operation, the voice coil  34 , voice coil bracket  54 , frame bracket  58  and spider  18  may be assembled as a unit or spider subassembly  87  outside of the frame  14 . See  FIG. 6 . Initially, the voice coil bracket  54  is mounted to the outer surface  40  of the former  36  in the position shown in  FIG. 5 . The lead wire  52  is connected to the voice coil lead  78  from the wire winding  42 . With the voice coil bracket  54  in place on the former  36 , the lead wire  52  is inserted through the guide  64  in the voice coil bracket  54 . Once the voice coil bracket  54  is mounted to the voice coil  34 , the inner diameter of the spider  18  is connected to the voice coil bracket  54  by gluing it to the lower seat  76 , and its outer diameter is glued to the seat  86  in the frame bracket  58 . The opposite end of the lead wire  52  may be inserted into the guide  80  of the frame bracket  58  after the spider  18  is in place. The entire spider subassembly  87  is then mounted to the speaker  10  by sliding the voice coil  34  over the pole piece  28  of the motor structure  12  until the foot  60  of the frame bracket  58  contacts the plateau  62  in the frame  14  where it is glued in place. The end of the lead wire  52  carried by the frame bracket  58  is then connected by soldering, clamping or the like to electrical connectors (not shown) mounted to the frame  14 . Finally, the lower end of the diaphragm  16  is slid over the voice coil former  36  until it engages the upper seat  74  of the voice coil bracket  54 . The surround  20 , which is connected to the diaphragm  16  at the factory, contacts the upper end  44  of the frame  14 . Both the diaphragm  16  and surround  20  are glued in place thus securing the entire moving assembly to the frame  14 . 
   As noted above, the lead wire  52  is preferably inserted through the guide  64  in the voice coil bracket  54  and through the guide  80  in the frame bracket  58  outside of the frame  14 . In the embodiment of  FIGS. 4-6 , the guides  64  and  80  of the voice coil bracket  54  and frame bracket  58 , respectively, are angled to cause the lead wire  52  to extend in an arc between the voice coil  34  and frame  14 . The angles of the guides  64  and  80 , and therefore the arc of the lead wire, are chosen to ensure that the lead wire  52  may readily move with the excursion of the voice coil  34  without stressing the connections of the lead wire  52  at either end or tending to pull the voice coil  34  in a side-to-side motion in the course of its movement within the magnetic gap  32 . Relief of stress on the lead wire  52  connections is also provided by the rounded edge of the outlet  70  of guide  64 , and the rounded inlet end  82  of the frame guide  58 . Additionally, the particular arc of the lead wire  52  is chosen to avoid contact of the lead wire  52  with the diaphragm  16  or spider  18 , and such arc can be altered depending on the size of the speaker  10  and the angle at which the diaphragm  16  extends between the surround  20  and voice coil  34 . Accordingly, the voice coil bracket  54  and the frame bracket  58  allow for precise control of the lead wire  52  arc and length, thus eliminating the guesswork and inconsistencies which plagued prior art speakers. Further, because many of the assembly operations can be performed outside of the frame  14 , the overall speaker assembly is greatly simplified and can be performed more quickly. 
   Referring now to  FIGS. 7-13 , alternative embodiments of the invention are shown which are similar in structure and operation to that discussed above in connection with  FIGS. 4-6 . In  FIGS. 7-9 , the same voice coil bracket  54  and frame bracket  58  are employed as in  FIGS. 4-6 , and they operate in the same manner as described above. The difference in this embodiment is that the voice coil bracket  54  is mounted to the voice coil former  36  in a position below the location where the lead wire  52  is connected to the voice coil lead  78 . In order to insert the lead wire  52  into the guide  64 , the voice coil bracket  54  is formed with a notch  88  as best seen in  FIG. 9 . 
   The embodiment depicted in  FIGS. 10 and 11  is the same as that shown in  FIGS. 7-9 , except that the lower edge of the diaphragm  16  is mounted directly to the former  36  of the voice coil  34  instead of to the upper seat  74  formed in the voice coil bracket  54 . Similarly, the embodiment depicted in  FIGS. 12 and 13  is the same as that shown in  FIGS. 4-6 , except, as in  FIGS. 10 and 11 , the lower edge of the diaphragm  16  is mounted directly to the former  36  of the voice coil  34  instead of to the upper seat  74  formed in the voice coil bracket  54 . 
   Referring now to  FIGS. 14-17 , a further embodiment of the speaker  10  is shown. In this embodiment, a voice coil bracket  89  is employed which is similar to the voice coil bracket  54  described in the previous embodiments except the lower seat  76  is eliminated and the voice coil bracket  89  is formed in an arc segment a ring which extends completely around the former  36  as in the voice coil bracket  54 . Each lead wire  52  is secured within the guide  64  of the bracket  89 , as in  FIGS. 7-11 , but the diaphragm  16  is mounted directly to the voice coil former  36  at a location above the bracket  89  and the inner diameter of the spider  18  is mounted to the former  36  below the bracket  89 . The outer diameter of the spider  18  is mounted to the frame plateau  48 . 
   Different frame brackets  90  are provided in the embodiment of  FIGS. 14-17  since the spider  18  is mounted to the plateau  48 . Each frame bracket  90  has a yoke  92  formed with at least one bore. The yoke  92  fits over an edge of the frame  14  so that its bore aligns with a bore in the frame  14 . These bores receive a screw  94  which secures the bracket  90  to the frame  14 . The upper portion of the frame bracket  90  has a guide  96  formed with a rounded, inlet end  98  and an outlet end  100 . One lead wire  52  is extended through the guide  96  of each frame bracket  90  so that its end is positioned to engage an electrical contact  102  carried by the frame bracket  90 . 
   The voice coil brackets  89  and frame brackets  90  perform the same functions in controlling the arc and length of the lead wires  52  as described above in connection with a discussion of  FIGS. 4-7 . The guides  64  and  96  are angled so that the arc of the lead wires  52  allows for free movement of the voice coil  34  without creating contact between the diaphragm  16  or spider  18  and the lead wires  52 . 
   Referring now to  FIGS. 18-21 , a still further embodiment of this invention is illustrated which is similar to that of  FIGS. 14-17  except in the construction of the frame bracket  104 . Instead of two separate frame brackets  90 , as employed in the embodiment of  FIGS. 14-17 , the frame bracket  104  depicted in  FIGS. 18-21  is a single unit having a yoke  106  which fits over the frame  14  so that aligning bores in the bracket  104  and frame  14  can receive a screw  108  to mount the two elements together. The bracket  104  has spaced guides  110 , each having a rounded inlet end  112  and an outlet end  114 , which receive one of the lead wires  52 . The end of each lead wire  52  is located in position to engage an electrical contact  116  carried by the bracket  104 . The embodiment of  FIGS. 18-21  is otherwise the same as in  FIGS. 14-17 , and operates in the same fashion. 
   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. 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.