HK1178726A - Earphone driver and method of manufacture - Google Patents

Description

Earphone driver and manufacturing method

Technical Field

The present invention relates to the field of sound reproduction, and more particularly to the field of sound reproduction using headphones. The invention of the present invention relates to headphones for ear bud listening devices ranging from self-hearing to high quality audio listening devices to consumer listening devices.

Background

Personal "ear-to-ear" monitoring is used by musicians, recording studio engineers and live sound engineers to monitor performances on stage and in recording studios. The ear-bud system delivers the music mix directly to the musicians or engineers' ears without competing with other stage or studio sounds. The system provides musicians or engineers with increased control over the balance and volume of instruments and tracks, and serves to protect the musicians or engineers' hearing through better sound quality at lower volume settings. Ear-bud listening systems provide an improved alternative to the common feedback enclosures (floor wedge) or speakers, and in turn have significantly changed the way musicians and sound engineers work on stages and in the studio.

In addition, many consumers want high quality audio sound whether they are listening to music, DVD songs, podcasts (podcasts) or cell phone calls. The user may want a small headset that effectively blocks background ambient sound from the user's external environment.

Hearing aids, ear bud systems, and consumer listening devices typically utilize an earpiece that engages at least partially inside the listener's ear. A typical earphone has one or more drivers or balanced armatures mounted within a housing. Typically, the output of sound from the driver(s) is transmitted through a cylindrical sound port or nozzle (mouthpiece).

Disclosure of Invention

The present invention provides a headphone driver assembly, in particular a balanced armature driver assembly. The headphone driver assembly may be used in any hearing aid, high quality listening device, or consumer listening device. For example, the present invention may be implemented in or in conjunction with the headset assemblies, drivers, and methods disclosed in the following documents: attorney docket No.010886.01320 entitled "Earphone Assembly," and attorney docket No.010886.01328 entitled "Drive Pin Forming method and Assembly for a Transducer," which are incorporated herein by reference in their entirety.

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. The following summary merely presents some concepts of the invention in a simplified form as a prelude to the more detailed description provided below.

In one exemplary embodiment, a balanced armature motor assembly is disclosed, comprising: an armature having a flexible reed; a pole piece including a pair of magnets; a spool comprising a first cutout, a second cutout, and a central post; a wire coil surrounding the bobbin, the wire coil having a first end and a second end; and a circuit board mounted to the bobbin. The circuit board comprises a first terminal and a second terminal. A drive pin is operatively connected between the reed and the paddle. The first end of the wire coil is secured to the first terminal of the circuit board and passes through the first cutout of the bobbin, and the second end of the wire coil is secured to the second terminal of the circuit board and passes through the second cutout of the bobbin. The first end of the wire coil is oriented along a first line tangent to the central post of the bobbin and the second end of the wire coil is oriented along a second line tangent to the central post of the bobbin. The circuit board includes a first notch and a second notch, the first end of the wire coil is positioned in the first notch of the circuit board, and the second end of the wire coil is positioned in the second notch of the circuit board. The first and second cuts in the bobbin may be formed in an L-shape.

In another exemplary embodiment, a method of forming a balanced armature motor assembly is disclosed that includes an armature having a flexible reed, a pole piece containing a pair of magnets, a bobbin, a wire coil, a drive pin, a paddle, and a circuit board having a first terminal and a second terminal. The method comprises the following steps: winding a first end of a wire around a central post positioned on the spool; placing a portion of the first end of the wire in a first notch positioned on the spool; winding a central portion of the bobbin with the wire to form the wire coil; positioning a portion of the second end of the wire in a second notch positioned on the spool; wrapping the second end of the wire around the center post; and attaching the first end of the wire to the first terminal and the second end of the wire to the second terminal. The method further comprises: cutting the first end of the wire between the first terminal and the center post and discarding a first remaining portion of the first end wrapped around the center post; and cutting the second end of the wire between the second terminal and the center post and discarding a second remaining portion of the second end wrapped around the center post. The first and second ends of the wire may be attached to the first and second terminals by a thermo-compression or soldering process.

In another exemplary embodiment, a balanced armature motor assembly is disclosed, comprising: an armature having a flexible reed; a pole piece housing the first magnet and the second magnet; a spool having at least one post extending therefrom; a wire coil surrounding the bobbin; a circuit board mounted to the bobbin; a drive pin operatively connected to the reed and paddle. A compressed polymeric material may be interposed between the first magnet and the post and between the second magnet and the post. The polymer material forces the first magnet and the second magnet into contact with the pole piece. The polymer material includes at least one glue dot secured to each of the first magnet and the second magnet or a plurality of glue dots positioned on each of the first magnet and the second magnet. The at least one post may comprise a pair of T-shaped posts. The at least one glue dot on the first magnet is positioned on a first side of the T-shaped column, and the at least one glue dot on the second magnet is positioned on a second side of the T-shaped column. The first magnet and the second magnet are further welded to the pole piece.

In another exemplary embodiment, a method of forming a balanced armature motor assembly comprising an armature having a flexible reed, a pole piece comprising a first magnet and a second magnet, a bobbin, a wire coil, a drive pin, a paddle, and a circuit board is disclosed. The method comprises the following steps: placing a polymer material over the first magnet and the second magnet; positioning the first magnet and the second magnet such that the polymer material contacts at least one post extending from the bobbin; placing the pole piece over the first magnet and the second magnet and compressing the polymer material such that the polymer material forces the first magnet and the second magnet into contact with the pole piece; and securing the first magnet and the second magnet to the pole piece. The polymer material includes an adhesive, and the adhesive may include a plurality of glue dots on each of the first magnet and the second magnet. The step of compressing the polymeric material may comprise moving the magnets inwardly towards each other. The securing step may include welding the first magnet and the second magnet to the pole piece. The at least one post may comprise a pair of T-shaped posts extending from the spool. In addition, the reed passes between the first magnet and the second magnet and is equidistant from the first magnet and the second magnet.

Drawings

Fig. 1 shows a perspective view of a prior art mount for assembling a balanced armature driver assembly.

Fig. 2 shows an enlarged perspective view of the prior art mount of fig. 1.

Fig. 3A shows a perspective exploded front left view of an exemplary embodiment of a balanced armature motor assembly as disclosed herein.

Fig. 3B shows another perspective exploded left front view of the balanced armature motor assembly in fig. 3A.

Fig. 3C shows a perspective exploded rear left view of the balanced armature motor assembly in fig. 3A.

Fig. 3D shows another perspective left exploded front view of the balanced armature motor assembly in fig. 3A.

Fig. 3E shows another perspective exploded rear left view of the balanced armature motor assembly in fig. 3A.

Fig. 3F shows another perspective exploded left front view of the balanced armature motor assembly in fig. 3A.

Fig. 3G shows another perspective exploded left front view of the balanced armature motor assembly in fig. 3A.

FIG. 4A shows an isometric left front view of the balanced armature motor assembly and nozzle base shown in FIG. 3A.

Fig. 4B shows another isometric left front view of the balanced armature motor assembly of fig. 3A.

Fig. 4C shows an isometric left rear view of the balanced armature motor assembly of fig. 3A.

Fig. 5A shows a bottom view of another exemplary embodiment of a balanced armature motor assembly disclosed herein.

Fig. 5A1 shows the exemplary embodiment in fig. 5A after an assembly operation.

FIG. 5B shows a left rear perspective top view of the spool shown in FIG. 5A.

Fig. 5C shows a rear view of the balanced armature motor assembly of fig. 5A.

Fig. 6A shows a front view of another exemplary embodiment of a balanced armature motor assembly prior to a welding operation as disclosed herein.

Fig. 6B shows the embodiment of fig. 6A after a welding operation.

Fig. 7 shows a bottom view of a pair of magnets and respective glue dots used in embodiments of the balanced armature motor assembly disclosed herein.

Fig. 8 shows an end view of the magnet and glue dot of fig. 7.

Fig. 9 shows a top view of another exemplary embodiment of an unassembled balanced armature motor assembly disclosed herein.

Fig. 10 shows a representative schematic of an exemplary embodiment disclosed herein.

Fig. 11A-11K illustrate an exemplary method of assembling a balanced armature motor assembly.

FIG. 12 shows a graph comparing glue dot size, percent compression, and force for exemplary embodiments disclosed herein.

Detailed Description

The invention is illustrated by way of example and not limited in the accompanying figures.

An exploded view of the balanced armature motor assembly is shown in fig. 3A-3G, and an assembled view of the balanced armature motor assembly 150 is shown in fig. 4A, 4B, and 4C. The balanced armature motor assembly 150 can be used with any headset ranging from a self-hearing to a high quality audio listening device to a consumer listening device.

As shown in fig. 3A and 4A, the balanced armature motor assembly 150 is generally comprised of an armature 156, upper and lower magnets 158A, 158B, pole pieces 160, a bobbin 162, coils 164, drive pins 174, and a flexure plate 167 or any suitable type of circuit board. The magnets 158A, 158B are secured to the pole piece 160 and are held in contact with the pole piece 160 by a plurality of glue dots 182, the plurality of glue dots 182 providing a resilient force against a pair of "T" -shaped posts 184 extending from the bobbin 162, as described in more detail herein. While so held in place, the magnets 158A, 158B may be welded to the pole piece 160, as described in more detail herein. The flexure 167 is a flexible printed circuit board mounted to the bobbin 162, and the free ends of the leads forming the coil 164 are secured to the flexure 167 (as discussed in further detail herein).

From a top view, the armature 156 is substantially E-shaped. In other embodiments, the armature 156 may have a U-shape or any other known suitable shape. The armature 156 has a flexible metal reed 166, the flexible metal reed 166 extending through the bobbin 162 and the coil 164 between the upper magnet 158A and the lower magnet 158B and positioned equidistant from the upper magnet 158A and the lower magnet 158B. The armature 156 also has two outer legs 168A, 168B, the two outer legs 168A, 168B lying substantially parallel to each other and being interconnected at one end by a connecting part 170. As illustrated in fig. 4A, reed 166 is positioned within an air gap 172 formed by magnets 158A, 158B. The two outer armature legs 168A and 168B extend along the outer side along the bobbin 162, coil 164 and pole piece 160. The coil 164 may be formed between the two flanges 171A, 171B. Two outer armature legs 168A and 168B are attached to the pole piece 160. The reed 166 may be connected to the paddle 152 by a drive pin 174. The drive pins 174 may be formed from a stainless steel wire or any other known suitable material.

The electrical input signal is routed to the flex board 167 via a signal cable comprising two conductors. Each conductor is terminated to one or more pads on the flexure 167 via a solder connection or any suitable fastening method, which electrically connect (via traces of the flexure 167) to respective terminals 178A, 178B as shown in fig. 5a 1. In one embodiment, the pads are larger than the terminal ends 178A, 178B, and thus are adapted to provide a larger surface area for purposes of connecting the signal cable conductors, which are relatively larger than the wires forming the coil 164. In one embodiment, the solder pads are positioned on the end of the flexure plate 167 generally opposite the terminal ends 178A, 178B, as shown in fig. 5A and 5A 1. Each of these terminals 178A, 178B is electrically connected to a respective lead 165A or 165B on each end of the coil 164. When a signal current flows through the signal cable and into the winding of the coil 164, magnetic flux is induced into the soft magnetic reed 166, and the coil 164 is wound around the soft magnetic reed 166. The polarity of the signal current determines the polarity of the magnetic flux induced in reed 166. The free end of the reed 166 is suspended between the two permanent magnets 158A, 158B. The magnetic axes of both permanent magnets 158A, 158B are aligned perpendicular to the longitudinal axis of reed 166. The lower face of the upper magnet 158A acts as a magnetic south pole, while the upper face of the lower magnet 158B acts as a magnetic north pole.

As the input signal current oscillates between positive and negative polarity, the free end of reed 166 causes its behavior to oscillate between the behavior of a magnetic north pole and the behavior of a magnetic south pole, respectively. When acting as a magnetic north pole, the free end of reed 166 is repelled from the north pole face of the lower magnet and attracted to the south pole face of the upper magnet. As the free end of the reed oscillates between north and south pole behavior, its physical position in the air gap 172 oscillates in the same manner, thus reflecting the waveform of the electrical input signal. The motion of the reed 166 alone acts as an extremely inefficient acoustic radiator due to its minimal surface area and the lack of an acoustic seal between its front and back surfaces. To improve the acoustic efficiency of the motor, a drive pin 174 is utilized to couple the mechanical motion of the free end of the reed 166 to an acoustic seal lightweight paddle 152 having a significantly larger surface area. The resulting acoustic volume velocity is then transmitted through the earpiece nozzle 212 and ultimately into the ear canal of the user, thus completing transduction of the electrical input signal to the acoustic energy detected by the user.

As shown in FIG. 5A, the flexure 167 is formed having a first terminal end 178A and a second terminal end 178B. In one embodiment, during assembly, the ends of the wires forming the coil 164 are secured to the flexure plate 167 at the first and second terminal ends 178A, 178B. In other words, a start lead (start lead)165A or first end of the coil 164 and a finish lead (finish lead)165B or second end of the coil 164 are attached to the terminals 178A, 178B. The flexure plate 167 may optionally include first and second notches 169A, 169B for permitting the start and end leads 165A, 165B of the coil 164 to rest in adjacent notches (or "L-shaped cuts" 176A, 176B as described later herein) in the underlying bobbin 162 without distorting or applying pressure to the flexure plate 167.

The spool 162 has a spool 163, along with a first post 180A, a second or center post 180B, and a third post 180C. The first, second and third posts 180A, 180B, 180C are used to position the flexure 167 onto the bobbin 162, and the second or center post 180B is further used to secure the wire during the coil winding process. More specifically, the second post 180B, in conjunction with the L-shaped cutouts 176A, 176B described later herein, serves to position the start lead 165A and the end lead 165B in position relative to the first and second terminals 178A, 178B for affixing to the first and second terminals 178A, 178B. The central post 180B may also be configured to contact the earphone housing once the earphone housing is assembled to provide stability in preventing the motor assembly 150 from moving within the earphone housing. Additionally, the center post 180B may help level the nozzle base 201 to keep the motor assembly 150 parallel to the plane of the paddle 152 while maintaining a desired spacing. As shown in fig. 5B, first and second L-shaped cutouts 176A, 176B may be provided on the bobbin 162 for properly positioning the start and end leads 165A, 165B over the first and second terminals 178A, 178B.

Specifically, the ends of the wire of the coil 164 forming the leads 165A, 165B pass through the L-shaped cutouts 176A, 176B, through the notches 169A, 169B of the flexure plate 167, diagonally over the terminal ends 178A, 178B of the flexure plate 167, and are wound around the central post 180B. It should be understood that the notches 169A, 169B are optional and are present in some embodiments in order to avoid interference between the leads 165A, 165B and the flexure 167. In other embodiments, the flexure plate 167 may not have notches 169A, 169B, and alternatively, may be configured in different shapes and configurations such that the leads 165A, 165B pass through the L-shaped cutouts 176A, 176B and over the terminal ends 178A, 178B without contacting any edge of the flexure plate 167.

The central post 180B and L-shaped cutouts 176A, 176B in the spool 164 help maintain the start lead 165A and end lead 165B in place over the terminals while the leads 165A, 165B are secured to the terminals 178A, 178B. This improves manufacturability of the motor assembly 150 such that when the coil 164 is formed about the bobbin 162, the terminal leads 165A, 165B of the coil 164 can be properly and consistently positioned on the flexure plate 167 and affixed to the terminals 178A, 178B. Positioning the leads 165A, 165B between the securing structure of the L-shaped cutouts 176A, 176B and the central post 180B ensures that a suitable and sufficient amount of wire from the leads 165A, 165B is in contact with the terminals 165A, 165B.

In one embodiment, during manufacture, wire is wound around a central portion or spool 163 of the bobbin 162 to form the coil 164. This winding procedure may be performed manually, may be performed using an automated machine driver, or may involve a combination of manual and automated steps. First, the wire is wound around the central post 180B approximately two to four times. Next, the wire is captured in a first L-shaped cut 176A positioned on the spool 162, passing through the first notch 169A. Next, the wire is wound around a reel 163 into several layers, where each layer has a certain number of turns. In one embodiment, the wire is wound around the reel 163 in eight (8) layers, with each layer having thirty-one turns of wire. The wire is then captured in a second L-shaped cut 176B positioned on the spool 162, passing through the second notch 169B. The wire is then wrapped around the central post 180B again for approximately two to four times. The wire may then be cut to form the finish lead 165B. This procedure optimally positions the start lead 165A and the end lead 165B over the terminals 178A, 178B for securing the start lead 165A and the end lead 165B to the terminals 178A, 178B, as described herein.

Once the start lead 165A and the end lead 165B are properly positioned over the terminals 178A, 178B, the start lead 165A and the end lead 165B may be secured to the terminals 178A, 178B by any known suitable method for connecting wires to metal terminals, such as by soldering or by a thermal compression process. Once the leads 165A, 165B are secured to the terminal ends 178A, 178B, the wires of the start lead 165A and the end lead 165B are cut near the second post 180B. Excess wire remaining around the central post 180B is trimmed so that excess wire can be removed and discarded. In an exemplary embodiment, the first end 165A of the wire is cut between the first terminal end 178A and the center post 180B and a first remaining portion of the first end wrapped around the center post is discarded, and the second end 165B of the wire is cut between the second terminal end 178B and the center post 180B and a second remaining portion of the second end wrapped around the center post 180B is discarded.

Thus, as shown in fig. 5A1, the resulting flexure 167 and bobbin 162 appear with the completed leads 165A, 165B secured to the terminal ends 178A, 178B. As shown in the resulting assembly of fig. 5A1, first end 165A of wire coil 164 is oriented along a first line tangent to central post 180B of bobbin 162, and second end 165B of wire coil 164 is oriented along a second line tangent to central post 180B of bobbin 162.

Fig. 1 and 2 show a prior art assembly method for mounting magnet 58 into a driver assembly. As shown in fig. 1 and 2, ten pole pieces 60 are loaded into the holder block 40 while the magnet 58 is mounted and held against the inner wall of each pole piece 60 using the removable flexible spacer 80. The transverse spacers 10 are also used to center the magnets along the walls of the upper and lower pole pieces 60. Next, the holder block 40 is installed in a laser welder, and each magnet is accurately welded to the pole piece 60 by two spot welds 61. Next, ten pole pieces 60 are removed and flipped to perform the same welding operation on the other end in order to fully secure the magnet. The coil and bobbin are then secured to the pole piece magnet sub-assembly by an adhesive.

In an exemplary embodiment according to various aspects of the present invention, as shown in fig. 3G and 7, a plurality of glue dots 182 are placed on the magnet 158, the plurality of glue dots 182 helping to hold the magnet 158 against the pole piece 160 during welding of the magnet to the pole piece 160. Although fig. 3G depicts four glue sites 182 on the magnets 158A, 158B and fig. 7 depicts two glue sites 182 on the magnets 158A, 158B, any suitable number of glue sites 182 is envisioned. Fig. 8 shows a side profile of glue sites 182 on magnets 158A, 158B. As shown in FIG. 8, in one embodiment, the glue sites 182 have a substantially hemispherical shape. In other embodiments, the glue sites 182 may take on a variety of shapes and configurations.

As shown in fig. 5A and 5B, the bobbin 162 incorporates two "T" shaped posts 184 extending from a front flange 171A on the bobbin 162 to position and support the magnet 158 and pole piece 160. The "T" shaped post 184 facilitates assembly of the magnet 158 to the pole piece 160. Fig. 9 shows glue point contacts 187 on opposing surfaces or sides of the "T" shaped post 184. As shown in fig. 6A, the "T" post 184 has a first side 185A and a second side 185B, and the magnets 158A, 158B are positioned on each of the first side 185A and the second side 185B of the "T" post 184, with the glue dot 182 in contact with the first side 185A and the second side 185B of the T-post 184. Although "glue dots" are described in this embodiment, the elastomeric glue or adhesive used may be in other shapes and configurations, such as tape or glue lines. In addition, other types of suitable polymers are also envisioned in place of glue sites. Additionally, it is also contemplated that glue may be placed on the first and second sides 185A, 185B of the "T" shaped post 184 or other suitable locations rather than on the magnet 158. In addition, other shapes and configurations of the "T" post are envisioned, for example, the post 184 may be made as a straight post, a leg, or a flat narrow strip.

The purpose of the glue dots 182 is to facilitate assembly of the magnets 158 into the pole pieces 160 and to provide an improved structure for the balanced armature driver assembly 150 in general. It is desirable to hold the magnets 158 tightly against the upper and lower walls of the pole piece 160. To complete the magnetic flux path, it is preferable for performance reasons to minimize or eliminate the presence of any air gap between the pole piece 160 and the magnet 158. The glue dots 182 provide a resilient spring-like structure to hold the magnet 158 tightly against the interior of the pole piece 160 while welding the magnet 158 to the pole piece 160. In the embodiment shown in fig. 6B, a plurality of weldments 161A-161D are placed between the magnets 158A, 158B and the pole piece 160. Thus, in one aspect, glue sites 182 replace and perform the function of flexible spacers 80 (see fig. 1 and 2) of the prior art. In addition to glue, other suitable polymers, such as cured silicone rubber, may also be secured to the magnet to provide this resilient function.

According to one embodiment of the present invention as shown in fig. 11A-11K, during assembly, the magnets 158 are positioned on either side of the "T" shaped post 184, compressed and/or "tipped forward" at their forward ends, and then captured by the pole piece 160 as the pole piece 160 slides over the magnets 158. In one embodiment, the assembly fixture 186 may be used to facilitate assembly of the magnet 158 to the bobbin 162 and the pole piece 160. In one embodiment, the assembly fixture 186 may be used to facilitate assembly of the magnet 158 to the bobbin 162 and the pole piece 160. In particular, the assembly fixture 186 holds and manipulates the magnet 158 while the pole piece 160 is added.

Fig. 11A shows the overall assembly fixture 186 and guide fork 188. Fig. 11B shows the assembled holder 186 prior to receiving the spool 162. As shown in fig. 11D, the guide fork 188 has a first wider region 191, a transition region 192, and a narrower region 193, all of which allow the magnets 158 to move closer together as the guide fork 188 moves inward. As shown in fig. 11B, the assembly fixture 186 has a notch 190 for supporting the bobbin 162 when assembling the magnet 158 and the pole piece 160 to the bobbin 162.

First, as shown in fig. 11C, the spool 162 is mounted in the fixing frame 186. Next, as shown in fig. 11D, the guide fork 188 is moved over the bobbin 162. Next, as shown in FIG. 11E, the magnet 158 is inserted over the first wider area 191 of the guide fork 188 by means of glue dots 182 positioned on the bobbin "T" shaped post 184. Fig. 11F and 11G show the guide fork 188 moved inward (to the left) into position so that the magnet 158 contacts the transition region 192 and is compressed as it enters the narrower region 193 of the guide fork 188 in order to bring the magnet 158 closer for placement of the pole piece 160. The elastomeric dots 182 are also compressed during assembly to force the magnets 158 against the pole pieces and also resist the force provided by the guide prongs 188.

As shown in fig. 11H, the pole piece 160 is next mounted over the magnet 158. At this point, the pole piece 160 is resting on top of the guide fork 188 and is positioned only halfway down over the magnet 158 to facilitate insertion of the magnet 158 into the pole piece 160. As shown in fig. 11I-11K, the guide fork 188 retracts (moves to the right) and the pole piece 160 is pushed down all the way over the magnet 158. The glue dot 182 is compressed, trapping the magnet 158 between the bobbin "T" post 184 and the pole piece wall. The entire assembly is then removed from the fixture 186 and the magnet 158 may then be later welded to the pole piece 160 using any suitable and known welding method, such as laser welding. Fig. 6B shows approximate weld locations 161A-161D between the magnets 158A, 158B and the pole piece 160. Thus, the glue dot 182 both secures the magnet 158 in place in the pole piece 160 and holds it in place until a later welding operation is performed.

In an embodiment, the glue may have an elongation property of 150% when fully cured, which provides sufficient compressibility. For manufacturing and operational consistency, it is preferable that the glue sites 182 have a consistent height (+/-0.001 ") and be accurately positioned on the magnets 158. This can be achieved by proper fixation and controlled dispensing of the adhesive. The flexibility of the glue dots 182 absorbs assembly tolerances while providing sufficient force to hold the magnets 158 against the pole pieces 160.

A suitable adhesive that may be used to form glue dots 182 is Dymax3013-T, which is a flexible elastomeric adhesive. However, other binders and suitable polymers are envisioned. In one embodiment, the glue dot 182 is shaped to be approximately hemispherical after being dispensed, and is "disk pie" (panned) under compression during the assembly procedure described in fig. 11A-11K.

The relative force provided by each glue dot is based on factors such as the material properties, the amount of compression, and the size of each dot. As shown in fig. 10, the glue dot 182 may be molded as a hemisphere with a radius (R) and the amount of force may be treated as a linear spring, except as follows: following the gap (z) between the bobbin and the magnet_gap) Linearly decreasing, the volume changes exponentially (to the third power) according to the following equation. In FIG. 10, the glue dot 182 is shown in an uncompressed state, while the magnet 158 and portions of the post 184 are shown in the illustration z_gapA typical compression interval less than radius R. An optimal design will match the adhesive dot size capability to the system tolerances that affect the gap.

The estimated force provided by the glue dot may be determined by displacing the volume (v) of the discharge_comp) Multiplied by a spring factor (e.g., modulus of elasticity) to calculate. Due to the complex nature of system behavior and incomplete "hemispheres," the exact force may not be easily predictable, but ratherFor design purposes, the graph shown in FIG. 12 illustrates example system tolerances (bobbin, magnet, pole piece), along with the varying effects of different glue dot heights.

The graph shows the compression of the glue sites as a percentage (%) on the x-axis versus the force (N) on the y-axis. The top line (dotted line) shows the comparison for a dot size of 0.004 inches, the middle line (dotted line) shows the comparison for a dot size of 0.003 inches, and the bottom line (solid line) shows the comparison for a dot size of 0.002 inches. The following feasible regions exist: it operates within a minimum physical condition "LMC" (maximum gap between bobbin and magnet) and a maximum physical condition "MMC" (minimum gap between bobbin and magnet). The LMC/MMC range of the part used to establish the gap is shown in FIG. 12 as the target design window. The target design window shows the acceptable area for the glue sites 182.

In an alternative embodiment, a structure known as "crush ribs" (crush ribs) may be molded to the bobbin to configure the magnets in the pole pieces. The rib may be positioned halfway back along the length of the post of the bobbin in the area below the outer edge of the magnet. This will also allow the magnets to be tilted toward each other at the front when the pole pieces are mounted over the magnets. When the pole piece is fully installed, the magnet will pivot back to a parallel position about the crush ribs and be forced against the wall of the pole piece by the crush ribs. A type of spring or rubber part is also required in this embodiment to maintain pressure against the magnet, holding it tightly against the pole pieces.

Aspects of the present invention have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the present invention will occur to those skilled in the art from a review of the entire disclosure. For example, those of skill in the art will appreciate that the steps illustrated in the illustrative figures may be performed in an order different than presented, and that one or more steps illustrated may be optional in accordance with aspects of the invention.

Reference numerals

10 transverse spacer

40 fixing frame block

58 magnet

60 magnetic pole piece

61 spot welded part

80 Flexible spacer

150 balanced armature motor assembly

152 blade

156 armature

158 magnet

158A upper magnet

158B lower magnet

160 magnetic pole piece

161A weldment/weld location

161B weldment/weld location

161C weldment/weld location

161D weldment/weld location

162 bobbin

163 reel

164 coil

165A Start lead/terminal lead/first end

165B end lead/terminal lead/second end

166 flexible metal spring leaf

167 flexure board

168A outer leg

168B outer leg

169A first notch

169B second recess

170 connecting parts

171A flange

171B flange

172 air gap

174 drive pin

176A first L-shaped incision

176B second L-shaped incision

178A first terminal

178B second terminal

180A first column

180B second or center post

180C third column

182 glue dots

184T shaped column

185A first side

185B second side

186 assembling fixing frame

187 glue point contact point

188 guide fork

190 notch

191 first wider region

192 transition region

193 narrower region

201 nozzle base

212 earphone nozzle

Claims (20)

1. A balanced armature motor assembly comprising:

an armature having a flexible reed;

a pole piece including a pair of magnets;

a spool comprising a first cutout, a second cutout, and a central post;

a wire coil surrounding the bobbin, the wire coil having a first end and a second end;

a circuit board mounted to the bobbin, the circuit board including a first terminal and a second terminal; and

a drive pin operatively connected between the reed and paddle; wherein the first end of the wire coil is secured to the first terminal of the circuit board and passes through the first cutout of the bobbin, and the second end of the wire coil is secured to the second terminal of the circuit board and passes through the second cutout of the bobbin.

2. The assembly of claim 1, wherein the first end of the wire coil is oriented along a first line tangent to the central post of the bobbin and the second end of the wire coil is oriented along a second line tangent to the central post of the bobbin.

3. The assembly of claim 1, wherein the circuit board includes a first notch and a second notch, and wherein the first end of the wire coil is positioned in the first notch of the circuit board and the second end of the wire coil is positioned in the second notch of the circuit board.

4. The assembly of claim 2, wherein the first and second cuts in the bobbin are L-shaped.

5. A method of forming a balanced armature motor assembly comprising an armature having a flexible reed, a pole piece containing a pair of magnets, a bobbin, a wire coil, a drive pin, a paddle, and a circuit board having a first terminal and a second terminal thereon, the method comprising:

a first end of a wire wound around a central post positioned on the spool;

placing a portion of the first end of the wire in a first cutout positioned on the spool;

winding a central portion of the bobbin with the wire to form the wire coil;

positioning a portion of a second end of the wire in a second cutout positioned on the spool;

wrapping the second end of the wire around the center post; and

attaching the first end of the wire to the first terminal and the second end of the wire to the second terminal.

6. The method of claim 5, further comprising cutting the first end of the wire between the first terminal and the center post and discarding a first remaining portion of the first end wrapped around the center post.

7. The method of claim 5, further comprising cutting the second end of the wire between the second terminal and the center post and discarding a second remaining portion of the second end wrapped around the center post.

8. The method of claim 4, wherein the first and second ends of the wire are attached to the first and second terminals by a thermal compression or soldering process.

9. A balanced armature motor assembly comprising:

an armature having a flexible reed;

a pole piece housing the first magnet and the second magnet;

a spool having at least one post extending therefrom;

a wire coil surrounding the bobbin;

a circuit board mounted to the bobbin;

a drive pin operatively connected to the reed and paddle; and

a compressed polymer material interposed between the first magnet and the post and between the second magnet and the post, the polymer material forcing the first magnet and the second magnet into contact with the pole piece.

10. The assembly of claim 9, wherein the polymer material comprises at least one glue dot secured to each of the first magnet and the second magnet.

11. The assembly of claim 10, wherein the polymer material comprises a plurality of glue dots positioned over each of the first magnet and the second magnet.

12. The assembly of claim 10, wherein the at least one post comprises a pair of T-shaped posts, and wherein the at least one glue dot on the first magnet rests on a first side of the T-shaped posts.

13. The assembly of claim 12, wherein the at least one glue dot on the second magnet rests on a second side of the T-shaped post.

14. The assembly of claim 9, wherein the first magnet and the second magnet are further welded to the pole piece.

15. A method of forming a balanced armature motor assembly comprising an armature having a flexible reed, a pole piece comprising a first magnet and a second magnet, a bobbin, a wire coil, a drive pin, a paddle, and a circuit board, the method comprising:

placing a polymer material over the first magnet and the second magnet;

positioning the first magnet and the second magnet such that the polymer material contacts at least one post extending from the bobbin;

placing the pole piece over the first magnet and the second magnet and compressing the polymer material such that the polymer material forces the first magnet and the second magnet into contact with the pole piece; and

securing the first magnet and the second magnet to the pole piece.

16. The method of claim 15, wherein the polymeric material comprises a binder.

17. The method of claim 16, wherein the adhesive comprises a plurality of glue dots on each of the first magnet and the second magnet.

18. The method of claim 15, wherein the step of compressing the polymeric material comprises moving the magnets inwardly toward each other.

19. The method of claim 16, wherein the securing step comprises welding the first magnet and the second magnet to the pole piece.

20. The method of claim 15, wherein the at least one post comprises a pair of T-shaped posts extending from the bobbin.