Patent Publication Number: US-11399235-B1

Title: Balanced armature receiver

Description:
TECHNICAL FIELD 
     This disclosure relates generally to balanced armature receivers and more specifically to balanced armature receivers having improved acoustic performance. 
     BACKGROUND 
     Balanced armature receivers (also referred to herein as “receivers” and “acoustic receivers”) capable of producing sound in response to an electrical input signal are known generally. Such receivers include a diaphragm disposed in a housing and separating an interior thereof into front and back volumes. A motor located in the back volume comprises a coil disposed about an armature a portion of which is movable between permanent magnets retained by a yoke when an electrical input signal is applied to the coil. The movable portion of the armature is linked to a movable portion of a diaphragm. Movement of the diaphragm creates sound that emanates from a sound port coupled to the front volume of the housing. The sound port is typically located on an end wall of the housing, but this location limits the size of the sound port, particularly in low profile receivers. However a small sound port limits the high frequency response of the receiver. Top-port receivers can accommodate larger sound ports, but top-port receivers are not suitable for many customer applications. 
    
    
     
       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  is a perspective sectional view of a balanced armature receiver including a paddle oriented at an angle in the housing. 
         FIG. 2  is a perspective sectional view of another balanced armature receiver including a paddle oriented at an angle in the housing. 
         FIG. 3  is a perspective sectional view of a balanced armature receiver including a curved paddle. 
         FIG. 4  is a partial perspective view of a balanced armature receiver with a ribbon linking an armature to a paddle of the receiver. 
     
    
    
     Those of ordinary skill in the art will appreciate that elements in the figures are illustrated for simplicity and clarity. It will be appreciated further that certain actions and/or steps may be described or depicted in a particular order of occurrence while those having ordinary skill in the art will understand that such specificity with respect to sequence is not actually 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 
     The disclosure relates generally to a balanced armature receiver comprising a diaphragm with a paddle orientated at an angle within a housing of the receiver. Such an orientation provides larger space on an end wall of the housing for the sound port, than would otherwise be available if the paddle was not orientated at an angle, without increasing the height of the receiver. 
     In  FIG. 1 , a receiver  100  comprises a housing  102  having an interior  104  containing a diaphragm  106  that separates an interior  104  of the housing into a front volume  110  and a back volume  112 . A motor  108  disposed in the back volume comprises a coil  132  magnetically coupled to an armature  136  having an end portion  148  movably disposed in a space  144  between magnets  138  retained by a yoke  134 . The armature  136  is coupled to a movable paddle  116  of the diaphragm, wherein the armature moves the paddle in response to an excitation signal applied to the coil. 
     In  FIG. 1 , the diaphragm includes a diaphragm body  114  comprising a paddle  116  flexibly coupled to a frame  118  by one or more hinges  120 . A gap separates at least a portion of the paddle from the frame and the gap is covered by a membrane described further herein. In  FIG. 1 , the diaphragm body is an unassembled unitary member comprising the paddle, frame and hinge. In other embodiments, the diaphragm body is an assembly formed by a discrete paddle flexibly fastened to a discrete frame. Alternatively, the diaphragm is devoid of a hinge and the paddle exhibits pseudo-pistonic motion when driven by the motor. In  FIGS. 2-3 , the paddles are also hinged to the frame. In other implementations however the paddles in  FIGS. 1-3  can be configured for pseudo-pistonic movement. In some implementations a portion of the housing constitutes the frame relative to which the paddle moves, with or without a hinge, and the gap is formed between the housing sidewall and the paddle. 
     The diaphragm also includes a flexible membrane bridging the gap between the paddle and the frame. The flexible membrane is configured to permit movement of the paddle relative to the frame without undue constraint. The membrane also forms an acoustic seal between the front and back volumes of the housing. An atmospheric relief vent is often formed in the diaphragm and can be formed in the membrane or paddle. In  FIG. 1 , the membrane  128  covers the gap between the paddle  116  and the frame  118  and has a profile that permits the paddle to move relative to the frame. In diaphragms devoid of a hinge, the membrane covers the gap between the perimeter of the paddle and the frame and permits pseudo-pistonic movement of the paddle when driven by the motor. The membrane can comprise urethane, Mylar, or a siloxane such as silicone, among other suitable materials. The flexible membrane may be applied as a layer or film disposed on an entire surface of the diaphragm body or on only select portions of the diaphragm body sufficient to cover the gap. 
     Generally, the armature is directly or indirectly coupled to the paddle. As shown in  FIGS. 1-4 , a linkage  130  couples the paddle to the armature  136 . In  FIGS. 1-3 , the linkage is a drive rod having one end  150  welded, glued or otherwise fastened to an end portion  148  of the armature and a second portion  152  fastened to a glue-filled opening the paddle. The glue is not shown for clarity. In  FIG. 4 , the linkage  130  is a ribbon comprising a first end  150  with an aperture at least partially surrounding the end portion of the armature  136  and a second portion  152  fastened to a glue-filled opening the paddle. Alternatively, the end  152  of the drive rods in  FIGS. 1-4  may be bent and fastened to an underside of the paddle by glue or another fastening mechanism. In other implementations, the armature is coupled directly to the paddle without an intermediate link. 
     An electric signal representing the sounds to be produced by the receiver are applied to the coil  132  which causes the armature  136  to vacillate and drive the paddle  116  in directions  140 , shown in  FIG. 1 . The movement of the paddle  116  creates sound that emanates through a sound port  142  acoustically coupling the front volume  110  to an exterior  170  of the housing. 
     In  FIG. 1 , the receiver housing comprises a ceiling  160  between a first end wall  162  and a second end wall  164  of the housing. The front volume is defined partly by space between the ceiling  160  and the diaphragm  106 . The paddle is oriented non-parallel to the ceiling, wherein a first end  166  of the paddle is proximate the first end wall  162  and a second end  168  of the paddle is proximate the second end wall  164 . The sound port  142  is disposed through a portion of the end wall  162 . 
     In  FIG. 2 , a major dimension  172  of the diaphragm is aligned with a major dimension  174  of the ceiling  160 , and the first end wall  162  and the second end wall  164  extend along minor dimension(s) of the ceiling and diaphragm, in corresponding yz-planes shown in compass  180 . In other implementations the receiver housing does not have major and minor dimensions. 
     In  FIG. 1 , a first end  166  of the paddle is spaced apart from the ceiling  160  by a first distance  182  and the second end  168  of the paddle is spaced apart from the ceiling by a second distance  184  (both along z-axes) less than the first distance.  FIGS. 2-3  also show the first end  166  of the paddle spaced farther apart from the ceiling than the second end of the paddle  168 . In  FIGS. 1-3 , the sound port is located on the end wall  162  of the receiver housing between the first end of the paddle and the ceiling. The angled orientation of the paddle relative to the ceiling provides space on the end wall  162  to accommodate a larger sound port  142 , than would otherwise be available if the paddle was parallel to the ceiling. The larger sound port provides an improved frequency response, particularly at higher frequencies. 
     In  FIGS. 1 and 2 , the paddle  116  is a substantially planar member and an angle  186  between the ceiling and the paddle ranges from about 3 degrees to about 10 degrees. More generally the angle can be as high as 20 degrees or more. The specific angle for any particular receiver implementation depends on dimensional constraints and performance requirements, among other factors. 
     In the  FIG. 3 , the paddle is a non-planar member having a substantial curved or arcuate portion  188  between the first end  166  and the second end  168 . A non-planar paddle having a substantial curve provides more space on the end wall of the housing, between an end of the diaphragm and the ceiling, than would otherwise be provided by a substantially planar paddle. For a given motor size, the space available on the end wall for the sound port can be increased by increasing the curvature of the paddle. As described herein, a paddle having a substantial bend or curve is a paddle having a curve greater than curves associated with features used to stiffen substantially planar paddles. Such stiffening features include ribs, so-called hats, curved edges, bump and other feature arrays formed in or on the paddle. 
     In one implementation, a dimension of the motor is less than a dimension of the diaphragm and the motor occupies only a portion of the back volume. Thus configured, the motor can be offset to one side of the back volume farthest away from the end portion of the paddle spaced farthest from the ceiling of the housing. Offsetting the motor in the back volume accommodates greater tilting of the paddle without increasing the height of the housing. Offsetting the motor in the back volume can also provide a mechanical advantage for actuating the paddle, depending where the armature is coupled to the paddle. In  FIGS. 1-3 , the motor (shown as  108  in  FIG. 1 ) is located more near the second end wall  164  than the first end wall  162  of the housing. In one implementation, the motor occupies approximately one-half of the back volume. However, in other implementations the motor can occupy more or less of the housing back volume, depending on the size of the motor, and the desired frequency response, among other considerations. Such a construction accommodates more paddle tilt thereby permitting a larger acoustic port on the housing end wall. In other implementations the motor extends along the full length of the back volume. 
     In some implementations, the armature can be connected to a mid-portion of the paddle. The “mid-portion” of the paddle as used herein means within about 15 percent of the middle of the paddle. Connecting the armature to the mid-portion of the paddle may be desirable for paddles that exhibit pseudo-pistonic movement (i.e., for paddles without a hinge). Connecting the armature to the mid-portion of a hinged paddle can provide mechanical advantage since coupling the armature to the paddle more near the hinge will provide greater paddle deflection for a given armature deflection. Offsetting the motor in the back volume can provide greater flexibility on where the armature is coupled to the paddle, without the need to relocate where the link is coupled to the armature. In  FIGS. 1-3 , motor is offset in the back volume away from the sound port, and the link is coupled to an end portion of the armature and to a mid-portion of the paddle. In  FIG. 1 , the paddle is flexibly hinged to the frame opposite the sound port  142  and the end portion  148  of the armature is coupled to the mid-portion of the paddle by the drive rod  130 . In  FIG. 2 , the paddle is flexibly hinged to the frame adjacent the sound port  142  and the end portion of the armature is coupled to the mid-portion of the paddle by the drive rod. In  FIG. 2 , there is a tradeoff between offsetting the motor to accommodate a larger sound port  142  and coupling the armature to the paddle in greater proximity to the hinge, since moving the motor more near the hinge may eventually interfere with the tilted paddle. In  FIG. 3 , the hinge for the substantially curved paddle is located opposite the sound port  142 . In an alternative embodiment, the hinge for the curved paddle can be located adjacent the sound port. In another implementation, the drive link is coupled to an end of the armature and to a location on the paddle that is less than about ⅔ a distance from the hinge to the opposite end of the paddle. 
     The paddle can comprise conventional materials like steel or aluminum. In implementations where the diaphragm body is a unitary member, the frame and hinge comprise the same material as the paddle. Implementations where the diaphragm body is an assembly, the frame can comprise the same or different material than the paddle. In one embodiment, the frame comprises aluminum, stainless steel, nickel, copper, among other materials and combinations thereof. 
     While the disclosure and what is presently considered to be the best mode thereof has been described in a manner establishing possession and enabling those of ordinary skill in the art to make and use the same, it will be understood and appreciated that there are many equivalents to the select embodiments described herein and that myriad modifications and variations may be made thereto without departing from the scope and spirit of the invention, which is to be limited not by the embodiments described but by the appended claims and their equivalents.