Abstract:
A receiver includes an acoustic module and a coil module. The acoustic module includes a first housing, a plurality of magnets, and an armature. The armature is disposed within the first housing and extends between the plurality of magnets. The coil module is coupled to the acoustic module, is physically separate from the acoustic module, and includes a second housing and a coil. The coil disposed within the second housing and does not surround the armature. The coil is excitable by an electrical current representative of acoustic energy and excitation of the coil produces a magnetic flux path which moves the armature.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/088,197, filed Dec. 5, 2014, entitled RECEIVER WITH COIL FREE REED which is incorporated by reference in its entirety herein. 
    
    
     FIELD OF THE INVENTION 
     This application relates to acoustic devices and, more specifically, to hearing aid receivers and their design. 
     BACKGROUND OF THE INVENTION 
     Various types of microphones and receivers have been used through the years. In these devices, different electrical components are housed together within a housing or assembly. For example, a receiver typically includes a coil, magnets, a reed, among other components and these components are housed within the receiver housing. Other types of acoustic devices may include other types of components. 
     In receiver applications, a coil is used to induce magnetic flux or field as electrical current is run through the coil. The magnetic field is induced into a ferromagnetic core which comprises a portion of a magnetic circuit. As the magnetic flux or field is induced into the magnetic circuit a portion of the magnetic circuit called the reed (or armature) is moved relative to the coil, this in turn moves a paddle, and sound is thereby created as the paddle moves the air. In some applications, the armature is configured to move air itself without the need of an attached paddle. The sound can consequently be presented to and heard by a listener. 
     In previous systems, the movable reed comprised at least a portion of the electromagnetic core of the coil, thus the coil had to be configured to provide a tunnel of space around the reed within which the reed is able to move unimpeded during normal operation of the receiver. In some versions, structures within the coil would be provided to impede motion of the reed during abnormal events such as the receiver striking a surface after being dropped. The coil would have to be constructed and assembled into the receiver with very tight tolerances, and the coils became expensive to build and complicated and expensive to integrate with the rest of the components of the receiver. 
     Another problem with previous approaches was that the coil was typically fit around the moving portion of the reed. Unfortunately, by winding the coil around the moving portion of the reed, the overall shape and configuration receiver was limited. 
     Another problem was that coils were often configured to match the electrical requirements of the specific application. With previous approaches, coils were deeply integrated into the construction of the receiver, and not removable or configurable after the initial manufacturing steps. As a result, manufacturing efficiency was lower due to lack of commonality early in the manufacturing process. 
     As a result of the disadvantages mentioned above, user dissatisfaction with previous approaches has resulted. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawings wherein: 
         FIG. 1  comprises a top cut-away view of a receiver according to various embodiments of the present invention; 
         FIG. 2  comprises a top cut-away view of the yoke assembly of the receiver of  FIG. 1  according to various embodiments of the present invention; 
         FIG. 3  comprises a top cut-away view of the coil module of the receiver of  FIG. 1  according to various embodiments of the present invention; 
         FIG. 4  comprises an external perspective view of the receiver of  FIG. 1  according to various embodiments of the present invention; 
         FIG. 5  comprises a magnetic circuit diagram of the receiver of  FIG. 1  according to various embodiments of the present invention; 
         FIG. 6  comprises a top-cut-away view of a two-coil receiver according to various embodiments of the present invention; 
         FIG. 7  comprises a magnetic circuit diagram of the receiver of  FIG. 6  according to various embodiments of the present invention; 
         FIG. 8  comprises a top cut-away view of another example of a two-coil receiver according to various embodiments of the present invention; 
         FIG. 9  comprises a side cut-away view of two-coil receiver of  FIG. 8  according to various embodiments of the present invention. 
     
    
    
     Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not necessarily required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. 
     DETAILED DESCRIPTION 
     Approaches are provided where one or more coils in receivers are configured to be fixedly attached to or directly wound upon a ferromagnetic core which comprises a portion of the magnetic circuit. So arranged, the coils do not require precision tolerances thereby making the coils significantly less expensive to manufacture as compared to previous coils. In addition, approaches are provided whereby one or more coils can be easily installed with other components to form a receiver module. In still another aspect, two (or potentially more) coils are provided and these coils are easily aligned with other magnetic components. The receivers provided herein have highly customizable designs, shapes, and dimensions, are easy to manufacture, and are significantly less expensive to produce as compared to previous devices. 
     Referring now to  FIGS. 1-5 , one example of a receiver  100  is described. The receiver  100  includes an acoustic module  102  and a coil module  150 . 
     The acoustic module  102  includes a reed  104  and a yoke assembly  106 . As used herein, the term “reed” is used interchangeably with “armature”. In any case, the term “reed” refers to a typically thin, flat and relatively long component that moves in the presence of a changing magnetic flux. The changing magnetic flux may be created by an electrical current that passes through a coil and interacts with magnetic fields produced by permanent magnets in a yoke assembly. In one example, the reed is constructed of soft magnetic steel, or “mu-metal”. Other examples of materials may be used to construct the reed. In another aspect, the reed  104  is constructed with thin and broad dimensions so as to act as a paddle. In one example, the reed  104  is 0.007 inch thin and 0.050 inch wide. One end of the reed  104  is attached (e.g., welded) to a soft magnetic steel bar  112  that protrudes from the receiver housing  142 ,  144 ,  146 . 
     The yoke body  107  is constructed of soft magnetic steel and includes magnets  108  and  109  attached to yoke body  107 . A hollow tunnel (or channel)  110  is formed and extends through the center of the yoke assembly  106 . One end portion of the reed  104  extends into the tunnel  110 . The other end portion of the reed  104  is attached to the bar  112 . In one example, the bar is constructed of a metal. 
     The coil module  150  includes a coil  152 . The coil  152  is wound around a soft magnetic steel core  154  that is attached to coil end portions  156  and  158 . The coil module  150  couples to the acoustic magnetic module  102 . It will be appreciated that since the coil module is secured to the acoustic magnetic module  102  and that the coil  152  is not wound around the moving portion of the reed  104 , the coil  152  remains stationary (or substantially stationary) during operation of the receiver  100 . It will be further appreciated that since the coil wire is tightly wound around the core, and that the wire is in contact with the core and does not form a tunnel within which the core could move with respect to the coil, as in previous receiver designs. 
     As can be seen in  FIGS. 1-5 , the moving portion of the reed  110  is not disposed down the axis of coil. Thus, the coil  152  does not need to be precisely placed or have a precise tolerance to avoid interference with the movement of the reed. 
     As mentioned and as shown, the coil  152  is not disposed on, around, or about the moving portion of the reed  104 . The proximity of the coil module  150  next to the acoustic magnetic module  102  is used during operation of the receiver to create a magnetic flux path  140 . As alternating current is applied to the coil  152 , the flux path  140  is created by the interaction of the electrical current in the coil and magnetic fields created by the permanent magnets  108  and  109 . The flux path  140  moves the reed  104 . More specifically, as the reed  104  moves, the air about the reed  104  moves thereby creating sound. In other words, the reed  104  acts as a diaphragm and no separate diaphragm element is needed. The sound tube receives the produced sound for presentation to a user. 
     In one aspect, the magnetic flux path  140  is closed and carries all static flux plus the worst case dynamic flux. The dynamic flux produced by the coil  152  splits the gap/channel  110  in twain, and has closed paths without requiring shunts. 
     The coil module  150  is a self-contained unit. The coil  152  is wire that is wound on a micro-metal core, encapsulated except on one face where micro-metal is exposed. A terminal is attached to coil module  150  to provide an electrical interface to the coil wire. 
     It will be appreciated that the receiver  100  can be easily customized by replacing coil module  150 . Thus, the size, shape, dimensions, performance characteristics, among other features of the coil module  150  can be customized to the particular needs and requirements of a particular acoustic module  102 . 
     The receiver  100  includes a top half cup housing portion  142 , a bottom half-cup housing portion  144 , and an end cap housing portion  146 . The housing portions  142 ,  144 , and  146  cannot be constructed of ferromagnetic materials but are instead constructed of some non-ferromagnetic material (such as plastic or hard stainless steel) that will not short the magnetic circuit. A terminal board  148  couples to the coil module  150  and provides a connection with external components. A reed magnetic terminal  149  extends from the bottom cup housing portion  144 . Yoke magnetic terminals  143  are exposed. The coil module has terminals  137  and  139  which couple respectively to terminals  149  and  143 . In so doing, the magnetic flux path  140  can be created. 
     In one example, a manufacturing process for creating the receiver  100  includes welding the thin, wide reed  104  to the bar  112 . In one aspect, the reed  104  may have a pie-pan shape to prevent flexing. Other examples of shapes may also be used. Then, a ring  113  welded to bar  112 . A thin film  114  is attached to ring  113  and reed  104 . 
     The yoke assembly  106  (including the yoke body  107 , and magnets  108  and  109 ) is placed over the reed  104 . In this respect, the position of the yoke assembly  106  is adjusted to center the reed  104  in the channel  110 . The yoke assembly  106  is affixed to the bottom half cup housing portion  144 , for example, using welding or glue. The top half-cup housing portion  142  and the end cap housing portion  106  are added (attached). The magnetic terminals (i.e., the exposed side of bar and yoke) are polished so as to provide an adequate magnetic connection. 
     The use of the detachable coil module  150  makes the present approaches highly customizable. In this respect, an appropriate coil module can then be attached to the module  102 . In addition, the cup housing portions mentioned above can also be exchanged out, for instance, to create more back volume in the receiver  100  as needed. For instance, housing portions having different dimensions, shapes, and configurations can be fitted to the particular needs of a particular receiver. In one example, a housing portion providing an increased back volume may be used to improve the performance characteristics of the receiver  100 . It will be appreciated that the cup housing portions  142 ,  144 , and  146  are the primary structured members of the receiver  100 . 
     Referring now to  FIG. 6  and  FIG. 7 , a receiver motor  600  with two coils is described. As shown, the receiver has a first coil  602  and a second coil  603 . The coils  602  and  603  include coil cores  610  and  612  and the coil cores  610  and  612  carry the static flux as well as the dynamic flux that is created during operation of the receiver  600 . The receiver  600  includes a reed  604 , a yoke assembly  606  (that includes a yoke body  607 , a first magnet  608 , and a second magnet  609 ). It can be appreciated that all the sources of magnetic radiation in the receiver  600  (i.e., the coil and magnets) are aligned. A tunnel  620  is disposed through the yoke assembly  606  and extends between the magnets  608  and  609 . In one aspect, the reed  604  is secured between the coils  602  and  603  and extends between the gap created by the tunnel  620  between the magnets  606  and  608 . 
     As can be seen in the receiver of  FIGS. 6 and 7 , the coils  602  and  603  are not disposed around the moving part of the reed  620 . Thus, the coils  602  and  603  do not need to be precisely placed or be constructed with precise tolerances. It will also be understood that although two coils are shown in this example (as well as the example of  FIGS. 8 and 9 ), any number of coils may be used. 
     In one example of the operation of the system of  FIG. 6  and  FIG. 7 , an alternating electrical current is generated and flow through the coils  602  and  603 . The flow of the alternating electrical current through the coils  602  and  603  interacts with the magnetic field produced by the magnets  608  and  609  to generate a magnetic flux. The magnetic flux flows in a direction indicated by the arrow labeled  622  down the reed  604  and moves the reed  604 . Reed  604  may then be attached to a paddle of a receiver, not show in  FIG. 6 . 
     Referring now to  FIGS. 8 and 9 , another example of a receiver  800  with two coils is described. As shown, the receiver  800  includes a first coil  802  and a second coil  803 . The coils  802  and  803  are wound about coil cores  810  and  812  and the coil cores  810  and  812  carry the static flux as well as the dynamic flux during operation of the receiver  800 . The receiver  800  includes a reed  804 , a yoke assembly  805  (that includes a yoke body  807 , a first magnet  808 , and a second magnet  809 ). It can be appreciated that all the sources of magnetic radiation in the receiver  800  (i.e., the coils and the magnets) are aligned. A tunnel  820  is formed in the yoke assembly  805  between the magnets  806  and  808 . The reed  804  is secured between coils and has a tongue  823  that extends in the tunnel  820 . An opening  821  extends through the reed  804 . 
     As can be seen in  FIGS. 8 and 9 , the coils  802  and  803  are disposed out of the tunnel  820 . Thus, the coils  802  and  803  do not need to be precisely placed or be constructed with precise tolerances. 
     In one example of the operation of the system of  FIG. 8  and  FIG. 9 , an alternating electrical current is generated and flow through the coils  802  and  803 . The flow of the alternating electrical current through the coils  802  and  803  interacts with the magnetic field produced by the magnets  808  and  809  to generate a magnetic flux. The magnets and coils are contained within a yoke assembly  805 . The magnetic flux flows in a direction indicated by the arrow labeled  622  (in  FIG. 6  which is also the equivalent magnetic circuit for the devices shown in  FIG. 8  and  FIG. 9 ) down the reed  804  and acts to move the tongue  823  of the reed  804 . Consequently, the reed  804  (and its tongue  823 ) acts as a diaphragm. As the reed  804  moves, the air around the reed  804  is moved thereby creating sound. The sound moves through the sound tube of the receiver  800  and after it exits the sound tube can be presented to a user. 
     It will be appreciated that in the approaches described herein, the sources of magnetic radiation are aligned. Because of the alignment, there is a much greater control of this magnetic radiation as compared to previous approaches. For instance, the amount and direction of created magnetic flux is better controlled. 
     Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. It should be understood that the illustrated embodiments are exemplary only, and should not be taken as limiting the scope of the invention.