Loudspeaker with dual coil, dual gap, electromagnetic transducer with outwardly offset voice coil

Abstract

A speaker includes a magnetic assembly having a top air gap and a bottom air gap spaced apart from each other along an axis. The speaker also includes a voice coil assembly having a bobbin having a top voice coil and a bottom voice coil. The spool is movable relative to the magnetic assembly in an upward direction and a downward direction along the axis, wherein at least one of the voice coils is respectively at least partially positioned within at least one of the air gaps. The voice coils are spaced apart from each other along an axis with an outward offset such that, in an average axial position of the spool, a portion of the top voice coil extending upward above the top air gap is larger than a portion of the top voice coil extending downward below the top air gap, and the part of the bottom voice coil extending downwards to the lower part of the bottom air gap is larger than the part extending upwards to the upper part of the bottom air gap.

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 701,152, filed on September 30, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to dual-coil, dual-gap, electromagnetic transducers for loudspeakers, and more specifically to a voice coil assembly configuration of such electromagnetic transducers. Background Technology

[0004] A loudspeaker includes an electroacoustic transducer for converting an electrical input into a sound output. The electroacoustic transducer includes a magnetic component, a voice coil assembly, and a diaphragm. The magnetic component and the voice coil assembly cooperate to function as an electromagnetic transducer. For a dual-coil electromagnetic transducer, the voice coil assembly includes two voice coils. In operation, the voice coil generates an electromagnetic field in response to being driven by an electrical input. The electromagnetic field interacts with the magnetic field of the magnetic component, causing the voice coil to move. The diaphragm, coupled to the voice coil, moves with the movement of the voice coil, thereby generating a sound output in the form of pressure sound waves. Summary of the Invention

[0005] A loudspeaker is provided. The loudspeaker includes a magnetic assembly and a voice coil assembly. The magnetic assembly has a top air gap and a bottom air gap spaced apart from each other along an axis. The voice coil assembly includes a spool having a top voice coil and a bottom voice coil. The spool is movable upward and downward relative to the magnetic assembly along the axis, wherein at least one of the top voice coil and the bottom voice coil is at least partially positioned within at least one of the top air gap and the bottom air gap, respectively. The top voice coil and the bottom voice coil are spaced apart from each other along the axis by being offset outward, such that, at an average axial position of the spool relative to the magnetic assembly, a portion of the top voice coil extending upward above the top air gap is greater than a portion extending downward below the top air gap, and a portion of the bottom voice coil extending downward below the bottom air gap is greater than a portion extending upward above the bottom air gap.

[0006] The portion of the top voice coil extending upwards above the top air gap and the portion of the bottom voice coil extending downwards below the bottom air gap may have the same length along the axis.

[0007] The top and bottom voice coils may have the same length along the axis. The top and bottom air gaps may also have the same length along the axis.

[0008] The top and bottom voice coils are offset outward and spaced apart from each other along the axis so that at the farthest upward axial position of the spool relative to the magnetic assembly, no part of the top voice coil is positioned within the top air gap, and only the bottommost part of the bottom voice coil is positioned within the bottom air gap.

[0009] The top and bottom voice coils are offset outward and spaced apart from each other along the axis so that at the farthest downward axial position of the spool relative to the magnetic assembly, only the uppermost portion of the top voice coil is positioned within the top air gap, and no portion of the bottom voice coil is positioned within the bottom air gap.

[0010] The top voice coil may consist of a first wire wound on the top portion of the spool in a first direction, and the bottom voice coil may consist of a second wire wound on the bottom portion of the spool in a second direction.

[0011] Another loudspeaker with a magnetic component and a voice coil assembly is provided. The magnetic component has a first air gap and a second air gap spaced apart from each other along an axis. The voice coil assembly includes a spool having a first voice coil and a second voice coil spaced apart from each other along an axis. The spool is movable relative to the magnetic component along the axis in a first direction and a second direction, wherein at least one of the voice coils is at least partially positioned within at least one of the air gaps. In the axial position of the spool relative to the magnetic component, the first voice coil extends a greater length through the first air gap in the first direction than it extends through the first air gap in the second direction, and the second voice coil extends a greater length through the second air gap in the second direction than it extends through the second air gap in the first direction.

[0012] A dual-coil, dual-gap electromagnetic transducer for a loudspeaker is provided. The electromagnetic transducer includes a magnetic assembly and a voice coil assembly. The magnetic assembly includes an annular central portion and an annular sleeve portion. The sleeve portion concentrically surrounds the central portion, with an air gap between the sleeve portion and the central portion. The central portion and the sleeve portion have a common central axis extending in an axial direction. The central portion includes a first top pole piece and a first bottom pole piece. The sleeve portion includes a second top pole piece and a second bottom pole piece. The top pole pieces are opposite each other to form a top air gap therebetween, and the bottom pole pieces are opposite each other to form a bottom air gap therebetween, wherein the top air gap and the bottom air gap are spaced apart from each other along a second axis extending in an axial direction. The voice coil assembly includes a spool having a top voice coil and a bottom voice coil spaced apart from each other along the second axis. The spool is movable upward and downward relative to the magnetic assembly along the second axis, wherein at least one of the top voice coil and the bottom voice coil is at least partially positioned within at least one of the top air gap and the bottom air gap, respectively. The top voice coil and the bottom voice coil are spaced apart from each other by being offset outward along the second axis, such that, at the average axial position of the spool relative to the magnetic assembly, the portion of the top voice coil extending upward above the top air gap is greater than the portion extending downward below the top air gap, and the portion of the bottom voice coil extending downward below the bottom air gap is greater than the portion extending upward above the bottom air gap. Attached Figure Description

[0013] Figure 1A An isometric cross-sectional view of a loudspeaker is shown, which includes a dual coil, a dual gap, and an electromagnetic transducer, the transducer consisting of a magnetic assembly including a first air gap and a second air gap, and a voice coil assembly including a first voice coil and a second voice coil.

[0014] Figure 1B It shows Figure 1A The image shows an enlarged view of a portion of the electromagnetic transducer;

[0015] Figure 2A A cross-sectional cut-angle view of the speaker is shown;

[0016] Figure 2B It shows Figure 2A An enlarged view of a portion of the electromagnetic transducer is shown;

[0017] Figure 3 A schematic cross-sectional representation of an electromagnetic transducer is shown;

[0018] Figure 4 A cross-sectional view of an electromagnetic transducer with magnetic flux lines and magnetic components showing the relative strength of the magnetic field;

[0019] Figure 5 A graph showing the magnetic field strength of the magnetic component passing through the first and second air gaps of the magnetic component; and

[0020] Figure 6A , Figure 6B and Figure 6C They are shown respectively Figure 1B , Figure 2B and Figure 3 A partial view showing the positioning of the first and second voice coils of the voice coil assembly within the first and second air gaps of the magnetic assembly. Figure 6C The view also includes a first set of annotations regarding the length attributes of the first voice coil and the first air gap, and a second set of annotations regarding the length attributes of the second voice coil and the second air gap. Detailed Implementation

[0021] This document discloses detailed embodiments of the present disclosure; however, it should be understood that the disclosed embodiments are merely examples of the present disclosure that may be embodied in various and alternative forms. The drawings are not necessarily to scale; some features may be enlarged or minimized to show details of components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but rather serve only as a representative basis for instructing those skilled in the art to employ the present disclosure in various ways.

[0022] Different naming conventions can be used to specify which pole of a magnet is north. Permanent magnets include magnetic polarity, where north pole is defined as the pole of the magnet that, when freely rotated, points towards the Earth's North Pole. Magnets described as having opposite or complementary polarities are positioned such that the north pole of the first magnet is closer to the south pole of the second magnet. Magnets described as having the same or similar polarities are aligned or positioned such that the north pole of the first magnet is closer to the north pole of the second magnet. Those skilled in the art will understand that any references to directions such as top, bottom, up, and down in the following description are made with reference to the described drawings and may differ in actual implementation depending on the orientation of the speaker, such as when it is mounted in the application.

[0023] Similarly, the orientation or alignment of a magnet can be described by referring to positive (+) and negative (-) magnetic poles. A magnetometer identifies magnetic polarity based on electromagnetic polarity, i.e., positive (+) and negative (-), rather than a geographical compass identifying north and south. A north-pointing compass (with positive magnetism) can be used to identify the negative magnetic field of a static permanent magnet. Positive and negative magnetic poles can be used to describe or specify the direction of magnetic flux flow.

[0024] Now for reference Figure 1A and Figure 2AThe images show a cross-sectional isometric view and a chamfered view of the loudspeaker 10. The loudspeaker 10 includes an electroacoustic transducer for converting an electro-audio signal input (i.e., an electrical representation of sound) into a sound output (i.e., sound). The electroacoustic transducer includes a magnetic assembly 12, a voice coil assembly 14, and a diaphragm 16. The magnetic assembly 12 and the voice coil assembly 14 cooperate to function as an electromagnetic transducer (also serving as a driver or motor). Figure 1B and Figure 2B They are shown respectively Figure 1A and Figure 2A An enlarged view of a portion of the electromagnetic transducer is shown.

[0025] In operation, the voice coil assembly 14 generates an electromagnetic field in response to an input electro-audio signal. The electromagnetic field is generated based on the input electro-audio signal. The electromagnetic field interacts with the magnetic field of the magnetic component 12, causing the voice coil assembly 14 to move. A diaphragm 16 (or cone) is coupled to the voice coil assembly 14 at one end. When the diaphragm 16 is coupled to the voice coil assembly 14, the diaphragm 16 moves in a corresponding manner to the movement of the voice coil assembly 14. This movement of the diaphragm 16 produces an acoustic output in the form of pressure sound waves. Thus, an electromagnetic transducer consisting of the magnetic component 12 and the voice coil assembly 14 can be used to drive the diaphragm 16 to produce an acoustic output corresponding to the input electro-audio signal.

[0026] More specifically, the speaker 10 also includes a frame or basket 18. The frame 18 includes a top base 20, a center base 22, and a bottom base 24 for supporting and securing the magnetic assembly 12. The frame 18 also includes a connecting structure 26 and a mounting flange 28. The connecting structure 26 generally extends outward and upward from the top base 20 to support the mounting flange 28.

[0027] The diaphragm 16 is coupled to the voice coil assembly 14 at one end and to the frame 18 at the other end. The diaphragm 16 is coupled to the frame 18 at a mounting flange 28. The coupling of the diaphragm 16 to the mounting flange 28 of the frame 18 is achieved via a surround 30. The surround 30 is a flexible suspension component. Coupling the diaphragm 16 to the frame 18 via the surround 30 allows the diaphragm 16 to move axially along the central axis of the loudspeaker 10, while preventing or minimizing lateral movement of the diaphragm 16.

[0028] The voice coil assembly 14 is arranged to move axially relative to the magnetic assembly 12 in a reciprocating or oscillating manner, that is, to move forward (i.e., upward toward the diaphragm 16) and backward (i.e., downward away from the diaphragm 16) along the central axis of the loudspeaker 10. The diaphragm 16 is coupled between the voice coil assembly 14 and the frame 18 such that the diaphragm 16 can move axially in a reciprocating or oscillating manner in response to the reciprocating or oscillating movement of the voice coil assembly 14, while preventing or minimizing lateral movement of the diaphragm 16.

[0029] The voice coil assembly 14 includes a voice coil skeleton or spool 32. The spool 32 is coupled to a diaphragm 16. Specifically, one end of the diaphragm 16 coupled to the voice coil assembly 14 is coupled to the spool 32. The spool 32 is also coupled to a frame 18. Specifically, the top portion of the spool 32 is coupled to the top base 20 of the frame 18; and the bottom portion of the spool 32 is coupled to the bottom base 24 of the frame 18. The top portion of the spool 32 is coupled to the top frame base 20 via a first spider 34; and the bottom portion of the spool 32 is coupled to the bottom frame base 24 via a second spider 36. Spiders 34 and 36 are flexible suspension components. Coupling the spool 32 to the frame 18 via spiders 34 and 36 allows the spool 32 to move axially relative to the magnetic assembly 12 along the central axis of the loudspeaker 10, while preventing or minimizing lateral movement of the spool 32.

[0030] The voice coil assembly 14 also includes a first voice coil 38 and a second voice coil 40. The first voice coil 38 and the second voice coil 40 are different coils. The first voice coil 38 and the second voice coil 40 are spaced apart from each other along the axial direction of the spool 32. The first voice coil 38 is wound around the top portion of the spool 32 the required number of turns. The second voice coil 40 is wound around the bottom portion of the spool 32 the required number of turns. The number of turns may be the same or substantially the same.

[0031] The wires forming the first voice coil 38 and the second voice coil 40 are wound on the spool 32 in opposite directions. For example, the first voice coil 38 is wound clockwise on the top portion of the spool 38, while the second voice coil 40 is wound counterclockwise on the bottom portion of the spool 32. With this configuration, the current of the audio signal flows through the first voice coil 38 in one direction and through the second voice coil 40 in the opposite direction. In this way, the polarities of the first voice coil 38 and the second voice coil 40 are reversed.

[0032] The magnetic assembly 12 includes a central portion 42 and a sleeve portion 44. The central portion 42 and the sleeve portion 44 each have an annular shape and share the central axis of the speaker 10 as a common central axis. The central portion 42 and the sleeve portion 44 are physically separated from each other. The sleeve portion 44 concentrically surrounds the central portion 42. Thus, the sleeve portion 44 is the "outer" portion of the magnetic assembly 12, while the central portion 42 is the "inner" portion of the magnetic assembly 12. Because the central portion 42 and the sleeve portion 44 are physically separated from each other, an air gap 45 is formed between them.

[0033] Both the central portion 42 and the sleeve portion 44 include a magnetic system. The magnetic systems generally have the same configuration. The magnetic system of the central portion 42 includes a top pole piece 46, a top permanent magnet 48, a central pole piece 50, a bottom permanent magnet 52, and a bottom pole piece 54. The components 46, 48, 50, 52, and 54 of the central portion 42 are stacked from front to back in the axial direction, in the listed order. Specifically, the top permanent magnet 48 is sandwiched between the top pole piece 46 and the central pole piece 50. The bottom permanent magnet 52 is sandwiched between the central pole piece 50 and the bottom pole piece 54. The components 46, 48, 50, 52, and 54 of the central portion 42 have an annular shape and are "inner" components because the central portion 42 is the inner portion of the magnetic assembly 12.

[0034] Similarly, the magnetic system of the sleeve portion 44 includes a top pole piece 56, a top permanent magnet 58, a center pole piece 60, a bottom permanent magnet 62, and a bottom pole piece 64. In this listed order, the components 56, 58, 60, 62, and 64 of the sleeve portion 44 are stacked from front to back in the axial direction. Specifically, the top permanent magnet 58 is sandwiched between the top pole piece 56 and the center pole piece 60. The bottom permanent magnet 62 is sandwiched between the center pole piece 60 and the bottom pole piece 64. The components 56, 58, 60, 62, and 64 of the sleeve portion 44 have an annular shape and are "external" components because the sleeve portion 44 is the outer portion of the magnetic assembly 12.

[0035] The permanent magnets 48 and 52 in the central portion 42 and the permanent magnets 58 and 62 in the sleeve portion 44 can be any known type of permanent magnet. In this example, permanent magnets 48, 52, 58, and 62 are neodymium magnets. Furthermore, as shown, permanent magnets 48, 52, 58, and 62 are neodymium-plated magnets.

[0036] The pole pieces 46, 50, and 54 of the central portion 42 and the pole pieces 56, 60, and 64 of the sleeve portion 44 can be made of any material with high magnetic permeability, which is used to guide the magnetic field generated by the permanent magnets 48, 52, 58, and 62. In this example, pole pieces 46, 50, 54, 56, 60, and 64 are steel pole pieces.

[0037] The magnetic system of the sleeve portion 44 also includes an additional component in the form of a ring 66. The ring 66 is positioned opposite the central portion 42. The inner side of the ring 66 is axially adjacent to the air gap 45. The outer side of the ring 66 is axially adjacent to the bottom portion of the top permanent magnet 58, the central pole piece 60, and the top portion of the bottom permanent magnet 62 of the sleeve portion 44. For example, the ring 66 is an aluminum ring.

[0038] As shown in the figure, components 46, 48, 50, 52, and 54 of the central portion 42 and corresponding components 56, 58, 60, 62, and 64 of the sleeve portion 44 are symmetrically aligned along the axial direction. Components 46, 48, 50, 52, and 54 of the central portion 42 and corresponding components 56, 58, 60, 62, and 64 of the sleeve portion 44 face each other across the air gap interval 45.

[0039] Air gap 45 physically separates components 46, 48, 50, 52, and 54 of the central portion 42 from their corresponding components 56, 58, 60, 62, and 64 of the sleeve portion 44. In this respect, a (top) magnetic air gap 68 is formed between the top pole pieces 46 and 56, and a (bottom) magnetic air gap 70 is formed between the bottom pole pieces 54 and 64. Specifically, the top air gap 68 is located between the tip 72 of the top pole piece 46 and the tip 74 of the top pole piece 56. Similarly, the bottom air gap 70 is located between the tip 76 of the bottom pole piece 54 and the tip 78 of the bottom pole piece 64.

[0040] The voice coil assembly 14, i.e., the spool 32 on which voice coils 38 and 40 are arranged, extends within the air gap 45. The voice coil assembly 14 extends within the air gap 45 such that at least one of the voice coils 38 and 40 is at least partially positioned within the top air gap 68 and the bottom air gap 70, respectively. As indicated above, the first support 34 and the second support 36 connect the top and bottom portions of the spool 32 to the top base 20 and the bottom base 24 of the frame 18, respectively. Thus, the spool 32 is suspended relative to the magnetic assembly 12 by the first support 34 and the second support 36, while the first voice coil 38 and the second voice coil 40 are positioned within the top air gap 68 and the bottom air gap 70, respectively. Since the spool 32 is axially movable relative to the magnetic assembly 12, the first voice coil 38 is axially movable relative to the top air gap 68 in correspondence to the axial movement of the spool 32, and the second voice coil 40 is axially movable relative to the bottom air gap 70 in correspondence to the axial movement of the spool 32.

[0041] As indicated, the electromagnetic transducer of the loudspeaker 10 comprises a magnetic assembly 12 and a voice coil assembly 14. As described, the electromagnetic transducer is a dual-coil, dual-gap electromagnetic transducer. The electromagnetic transducer is "dual-coil" because the voice coil assembly 14 includes a first voice coil 38 and a second voice coil 40. The electromagnetic transducer is "dual-gap" because the magnetic assembly 12 includes a top air gap 68 and a bottom air gap 70.

[0042] A first feature of the configuration of the magnetic assembly 12 is that the tips of the top and bottom poles expand relative to each other along the air gap (compared to the rest of the poles), such as... Figure 1A , Figure 1B , Figure 2A and Figure 2BAs shown. The expanded profile of the tip (“tip”) of the electrode is a truncated triangular shape, wherein the top pointed portion extends upward from the tip axis, while the bottom pointed portion extends downward from the tip axis. The expanded profiles of opposite electrode tips are generally symmetrical to each other.

[0043] Therefore, relative to the top air gap 68, the inner tip 72 of the top pole piece 46 and the outer tip 74 of the top pole piece 56 are expanded and relatively enlarged. Following an expanded profile, the top tip portion 80 extends axially upward from the inner tip 72, while the bottom tip portion 82 extends axially downward from the inner tip 72. Similarly, following an expanded profile, the top tip portion 84 extends axially upward from the outer tip 74, while the bottom tip portion 86 extends axially downward from the outer tip 74. Compared to pole pieces without this expanded profile, the expanded profiles of pole pieces 72 and 74 allow the first voice coil 38 to undergo more excursion across the top air gap 68.

[0044] In a similar manner, the inner tip 76 of the bottom pole piece 54 and the outer tip 78 of the bottom pole piece 64 are also expanded relative to the bottom air gap 70. The expanded profiles of the tips 76 and 78 allow the second voice coil 40 to make relatively more displacement across the bottom air gap 70.

[0045] As described and shown, the pole tip expands toward the air gap. In the example shown, the pole tip expands toward the air gap beyond the end of the permanent magnet.

[0046] A second feature of the configuration of the magnetic assembly 12 is that the sleeve portion 44 includes at least one permanent magnet. That is, the sleeve portion 44 is not merely a pole piece, for example, not merely a component made entirely of steel, but also includes a top permanent magnet 58 and a bottom permanent magnet 62.

[0047] As described above, the top permanent magnet 58 and bottom permanent magnet 62 of the sleeve portion 44 are axially aligned with the top permanent magnet 48 and bottom permanent magnet 52 of the central portion 42. The top permanent magnets 48 and 56 are associated with a top air gap 68. The bottom permanent magnets 52 and 62 are associated with a bottom air gap 70. The permanent magnets 48 and 52 of the central portion 42 are positioned to have the same first magnetic polarity 88. Figure 3 (Referring to the reference numerals shown). The permanent magnets 58 and 62 of the sleeve portion 44 are positioned to have the same second magnetic polarity 90 ( Figure 3 (As shown by reference numerals), the second magnetic polarity is opposite to the first magnetic polarity 88. Therefore, the magnetic field polarities of the central portion 42 and the sleeve portion 44 are reversed.

[0048] In this way, the magnetic component 12 generates a magnetic field that extends from the top pole piece 46 to the top permanent magnet 48, the center pole piece 50, the bottom permanent magnet 52, and the bottom pole piece 54 in the central portion 42, across the bottom air gap 70, and from the bottom pole piece 64 to the bottom permanent magnet 62, the center pole piece 60, the top permanent magnet 58, and the top pole piece 56 in the sleeve portion 44, and across the top air gap 68 to return to the top pole piece 46 in the central portion 42.

[0049] As described, according to a first feature of the configuration of the magnetic assembly 12, the top pole pieces 46 and 56 associated with the top air gap 68 and the bottom pole pieces 54 and 64 associated with the bottom air gap 70 have enlarged air gap pole tips, and according to a second feature of the configuration of the magnetic assembly 12, the sleeve portion 44 includes a top permanent magnet 58 and a bottom permanent magnet 62 having magnetic polarities opposite to those of the central portion 42.

[0050] According to the first feature, the enlarged air gap tips associated with the air gap provide greater displacement of the associated voice coil across the air gap. For example, the enlarged air gap tips of the top poles 46 and 56 provide greater displacement of the first voice coil 38 across the top air gap 68. Similarly, the enlarged air gap tips of the bottom poles 54 and 64 provide greater displacement of the second voice coil 40 across the bottom air gap 70. However, the enlarged air gap tips tend to result in a reduction in the strength of the magnetic field extending across the associated air gap.

[0051] According to the second feature, adding permanent magnets to the sleeve portion 44 of the air gap adjacent to and associated with the enlarged air gap tip increases the strength of the magnetic field extending across the associated air gap. For example, a top permanent magnet 58 in the sleeve portion 44 adjacent to the top air gap 68 increases the strength of the magnetic field extending across the top air gap. For example, a bottom permanent magnet 64 in the sleeve portion 44 adjacent to the bottom air gap 70 increases the strength of the magnetic field extending across the bottom air gap.

[0052] Incidentally, the first and second features of the magnetic component 12 have already been described in the context of a dual-coil, dual-gap, electromagnetic transducer. Thus, the first feature provides two pairs of enlarged air gap poles, and the second feature provides two permanent magnets incorporated into the sleeve portion. Of course, if desired, for such a dual-coil, dual-gap, electromagnetic transducer, only one pair of enlarged air gap poles can be provided for either of the two air gaps, and / or only one permanent magnet can be incorporated into the sleeve portion adjacent to either of the two air gaps. Similarly, the first and second features of the magnetic component 12 are applicable to the context of a single-coil, single-gap, electromagnetic transducer. In this case, the first feature provides a pair of enlarged air gap poles, and the second feature provides one permanent magnet incorporated into the sleeve portion.

[0053] Compared to the configuration of magnetic assembly 12, conventional magnetic assemblies have the following properties. Conventional magnetic assemblies include permanent magnets only in the central portion. That is, conventional magnetic assemblies do not include permanent magnets in the sleeve portion. Furthermore, the sleeve portion of a conventional magnetic assembly is entirely composed of magnetic pole material (e.g., the sleeve portion is simply a steel cylinder). In conventional magnetic assemblies, the pole pieces in both the central and sleeve portions are flat (e.g., the pole pieces are flat steel sheets). This allows the air gap to be closer to the center of the pole pieces, typically located at the surface where the permanent magnet and pole pieces meet in the central portion. This, along with the pole piece thickness, limits the amount of displacement the diaphragm can move through via the voice coil assembly. Moreover, for this type of motor (i.e., tightly spaced steel with high-energy magnets), there is more magnetic field leakage between the air gap from the sleeve portion to the central portion, resulting in magnetic field asymmetry and increased distortion.

[0054] As described, in the magnetic assembly 12, the magnetic field strength is increased by adding permanent magnets 58 and 62 to the sleeve portion 44. These additional magnets (i.e., "secondary magnets") drive the enlarged tips of the pole pieces 46, 56 and 54, 64 to saturation, thereby reducing distortion. The enlarged pole tips allow for more displacement than flat pole pieces. The enlarged pole tips help to better define the air gap area and keep the air gap spacing 45 at the designed amount. The more defined air gap between the center portion 42 and the sleeve portion 44, as well as the additional spacing via the air gap spacing 45, reduces magnetic flux leakage and makes the magnetic field lines in the air gap more symmetrical, thus reducing distortion.

[0055] In summary, in the magnetic component 12, the expanded profile of the pole tip, combined with the permanent magnet in the sleeve portion, enhances the magnetic field strength and fidelity across the air gap compared to pole tips without such an expanded profile and sleeve portions without such a permanent magnet. Thus, the dual-coil, dual-gap electromagnetic transducer composed of the magnetic component 12 is a dual-coil driver with enhanced saturation pole tips, or more simply, an enhanced dual-coil motor.

[0056] Now for reference Figure 3 Referring again to the preceding figures, a schematic cross-sectional representation of a dual-coil, dual-gap electromagnetic transducer is shown. In this example, the pole pieces of both the center portion 42 and the sleeve portion 44 are made of steel, such as "1010" steel; the permanent magnets of both the center portion 42 and the sleeve portion 44 are made of neodymium, such as "40" neodymium. The conductors of both voice coils 38 and 40 can be copper-clad aluminum (CCA) conductors, such as "23 AWG 10% CCA" conductors. In this example, the ring 66 is made of aluminum, such as "1100" aluminum.

[0057] Now for reference Figure 4Referring again to the preceding figures, a cross-sectional view of an electromagnetic transducer showing the relative strength of the magnetic field with flux lines 92 and magnetic component 12 is shown. Notably, the flux lines 92 are relatively uniform, with relatively low losses. Further noteworthy is that the symmetrical flux lines 92 extend across the top air gap 68 and the bottom air gap 70.

[0058] Now for reference Figure 5 And continue to refer to Figure 4 A graph 100 shows a curve 102 of the magnetic field strength of the magnetic component 12 through the top air gap 68 and the bottom air gap 70. The first peak 104 of the curve 102 indicates the strength of the magnetic field through the top air gap 68 (measured along the y-axis of the graph 100), and the second peak 106 of the curve indicates the strength of the magnetic field through the bottom air gap 70.

[0059] Now for reference Figure 6A , Figure 6B and Figure 6C The configuration of the voice coil assembly 14 will be described in more detail. Figure 6A , Figure 6B and Figure 6C They are shown respectively Figure 1B , Figure 2B and Figure 3 A partial view showing the positioning of the first voice coil 38 and the second voice coil 40 (i.e., the "top" voice coil 38 and the "bottom" voice coil 40) of the voice coil assembly 14 within the top air gap 68 and the bottom air gap 70 of the magnetic assembly 12. Figure 6C The view also includes a first set of notes 110 relating to the axial length properties of the first voice coil 38 and the top air gap 68, and a second set of notes 120 relating to the axial length properties of the second voice coil 40 and the bottom air gap 70.

[0060] like Figure 6A , Figure 6B and Figure 6C Of the best of each, the configuration of the voice coil assembly 14 is characterized in that the axial positioning of voice coils 38 and 40 within air gaps 68 and 70 is eccentric. Due to this eccentricity, at any moment when voice coils 38 and 40 move axially in response to the axial movement of the spool 32 of the voice coil assembly 14, neither voice coil 38 nor 40 is centered in the air gaps 68 and 70. Of course, in some cases where the spool 32 moves axially, one (but not both) voice coil may be centered in its air gap.

[0061] Furthermore, the eccentric positioning has an outward offset because voice coils 38 and 40 are axially further apart from each other relative to their center positions. In other words, the eccentric positioning of voice coils 38 and 40 is an outward-off offset. Due to this outward offset, voice coil 38 is positioned relatively far from the top gap 68 in the forward (upward) direction, while voice coil 40 is positioned relatively far from the bottom gap 70 in the rear (downward) direction.

[0062] Because voice coils 38 and 40 are offset outward and spaced further apart axially, the displacement of voice coil assembly 14 relative to the center positioning of voice coils 38 and 40 is extended. The “displacement” of voice coil assembly 14 is the axial movement of voice coil assembly 14 relative to the magnetic assembly 12 at its furthest point in the upward direction and at its furthest point in the downward direction. The furthest point of voice coil assembly 14 in the upward direction corresponds to the axial positioning of voice coil assembly 14 such that no part of voice coil 38 is positioned within the top air gap 68, and only the outermost portion (i.e., the lowermost portion) of voice coil 40 is partially positioned within the bottom air gap 70. The furthest point of voice coil assembly 14 in the downward direction corresponds to the axial positioning of voice coil assembly 14 such that only the outermost portion (i.e., the uppermost portion) of voice coil 38 is partially positioned within the top air gap 68, and no part of voice coil 40 is positioned within the bottom air gap 70.

[0063] Figure 6A , Figure 6B and Figure 6C Voice coils 38 and 40, which are spaced further apart axially due to their outwardly offset eccentric positioning, are best illustrated in this respect. Figure 6A , Figure 6B and Figure 6CThe diagram shows the voice coil assembly 14 in an average axial position relative to the magnetic assembly 12. Of course, the average axial position is just one of many different axial positions that the voice coil assembly 14 can present during operation of the loudspeaker 10. In the average axial position of the voice coil assembly 14, the eccentric positioning of the voice coils 38 and 40 in the top air gap 68 and the bottom air gap 70 is mirrored, wherein the same first number of coils 38 and 40 extend axially outward from the outer side of the top air gap 68 and the bottom air gap 70, and the same second number of coils 38 and 40 extend axially inward from the inner side of the top air gap 68 and the bottom air gap 70. (The first number of voice coils 38 extending axially outward from the outside of the top air gap 68 is the portion of voice coil 38 extending upward from the uppermost side of the top air gap 68; the first number of voice coils 40 extending axially outward from the outside of the bottom air gap 70 is the portion of voice coil 40 extending downward from the lowermost side of the bottom air gap 70; the second number of voice coils 38 extending axially inward from the inside of the top air gap 68 is the portion of voice coil 38 extending downward from the lowermost side of the top air gap 68; the second number of voice coils 40 extending axially inward from the inside of the bottom air gap 70 is the portion of voice coil 40 extending upward from the uppermost side of the bottom air gap 70.)

[0064] The first extension is greater than the second extension because the portion of coils 38 and 40 extending axially outward from the outside of air gaps 68 and 70 is greater than the portion of coils 38 and 40 extending axially inward from the inside of air gaps 68 and 70.

[0065] refer to Figure 6C The outward offset and eccentric positioning of voice coils 38 and 40 will be further described with reference to the first set of notes 110 (which relates to the axial length properties of voice coil 38 and top air gap 68) and the second set of notes 120 (which relates to the axial length properties of voice coil 40 and bottom air gap 70). The first set of notes 110 is intended to be shown as... Figure 6C The voice coil 38 and top gap 68 are shown to be axially aligned; the second set of notes 120 is intended to be shown as... Figure 6C The voice coil 40 and bottom gap 70 shown are axially aligned.

[0066] As shown in the first set of notes 110 and the second set of notes 120, voice coil 38 has a total length TL 112, and voice coil 40 has a total length TL 122. The first extension of coil 38 extending axially outward (i.e., upward) from the outer side (i.e., uppermost side) of top gap 68 has an outward length OL 114. The first extension of coil 40 extending axially outward (i.e., downward) from the outer side (i.e., lowermost side) of bottom gap 70 has an outward length 124. The second extension of coil 38 extending axially inward (i.e., downward) from the inner side (i.e., lowermost side) of top gap 68 has an in-box length IL 116. The second extension of coil 40 extending axially inward (i.e., upward) from the inner side (i.e., uppermost side) of bottom gap 70 has an inward length 126. Top gap 68 has a gap length GL 118, and bottom gap 70 has a gap length 128.

[0067] In this example, voice coils 38 and 40 have the same total lengths 112 and 122, the same outward lengths 114 and 124, and the same inward lengths 116 and 126, and the top gap 68 and the bottom gap 70 have the same gap lengths 118 and 128. Therefore, the total length 112 of voice coil 38 is equal to the sum of the outward length 114, the inward length 116, and the gap length 118 of top gap 68. Similarly, the total length 122 of voice coil 40 is equal to the sum of the outward length 124, the inward length 126, and the gap length 128 of bottom gap 70.

[0068] In other examples, voice coils 38 and 40 may have different total lengths, different outward lengths and / or different inward lengths, and / or top gap 68 and bottom gap 70 may have different gap lengths.

[0069] Furthermore, as can be seen from the comparison of notes 110 and 120, voice coils 38 and 40 have an outward offset because the outward lengths 114 and 124 are greater than the inward lengths 116 and 126. This is because voice coils 38 and 40 are spaced further apart axially when eccentrically positioned.

[0070] As indicated, the amount by which the voice coils extend inward from gaps 68 and 70 and outward from gaps 68 and 70 determines the amount of travel of both voice coils 38 and 40 within their gaps (minimum distortion) and the amount of travel of one voice coil within its gap (higher distortion level, but more like a typical loudspeaker). In the case of eccentric positioning, voice coils 38 and 40 are spaced further apart axially, with more voice coils extending beyond gaps 68 and 70 to achieve greater overall displacement.

[0071] Voice coils 38 and 40 are spaced further apart axially due to their outward offset and eccentric positioning, enabling greater displacement capability compared to conventional designs without increasing voice coil wire length or sacrificing efficiency. Distortion remains low at small displacements, but at other displacements, the loudspeaker 10 will place one of voice coils 38 and 40 within gaps 68 and 70, thereby controlling the diaphragm 16 and maintaining distortion comparable to conventional designs. The benefit is the ability to achieve increased displacement. This displacement helps improve the output sound level of the loudspeaker 10 and achieve deeper bass.

[0072] As described, in the dual-coil, dual-gap, electromagnetic transducer, two air gaps 68 and 70 are employed, which are driven by a magnetic component 12 with field return, such that magnetic flux passes through the two air gaps in its circuitry. The two air gaps 68 and 70, together with the two voice coils 38 and 40, are used to drive the same diaphragm 16 to produce sound.

[0073] While exemplary embodiments have been described above, these embodiments are not intended to describe all possible forms of this disclosure. Rather, the terms used herein are descriptive rather than limiting, and it should be understood that various changes may be made without departing from the spirit and scope of this disclosure. Furthermore, features of various embodiments may be combined to form other embodiments of this disclosure.

Claims

1. A loudspeaker comprising: a magnetic assembly having a top air gap and a bottom air gap spaced apart from each other along an axis; and a voice coil assembly including a bobbin having a top voice coil and a bottom voice coil, the bobbin being movable up and down relative to the magnetic assembly along the axis, wherein at least one of the top voice coil and the bottom voice coil is positioned at least partially within at least one of the top air gap and the bottom air gap, respectively; and wherein the top voice coil and the bottom voice coil are spaced apart from each other along the axis with an outward offset such that, at an average axial position of the bobbin relative to the magnetic assembly, a portion of the top voice coil extending upward above the top air gap is greater than a portion extending downward below the top air gap, and a portion of the bottom voice coil extending downward below the bottom air gap is greater than a portion extending upward above the bottom air gap.

2. The loudspeaker of claim 1, wherein: the portion of the top voice coil extending upward above the top air gap and the portion of the bottom voice coil extending downward below the bottom air gap have a same length along the axis.

3. The loudspeaker of claim 1, wherein: the portion of the top voice coil extending downward below the top air gap and the portion of the bottom voice coil extending upward above the bottom air gap have a same length along the axis.

4. The loudspeaker of claim 1, wherein: the portion of the top voice coil extending upward above the top air gap and the portion of the bottom voice coil extending downward below the bottom air gap have a same first length along the axis; and the portion of the top voice coil extending downward below the top air gap and the portion of the bottom voice coil extending upward above the bottom air gap have a same second length along the axis.

5. The loudspeaker of claim 4, wherein: the top voice coil and the bottom voice coil have a same third length along the axis.

6. The loudspeaker of claim 5, wherein: the top air gap and the bottom air gap have a same fourth length along the axis.

7. The loudspeaker of claim 1, wherein: the top voice coil and the bottom voice coil are spaced apart from each other along the axis with the outward offset such that, at a farthest upward axial position of the bobbin relative to the magnetic assembly, the top voice coil is positioned with no portion within the top air gap and only a lowermost portion of the bottom voice coil is positioned within the bottom air gap.

8. The loudspeaker of claim 1, wherein: the top voice coil and the bottom voice coil are spaced apart from each other along the axis with the outward offset such that, at a farthest downward axial position of the bobbin relative to the magnetic assembly, only an uppermost portion of the top voice coil is positioned within the top air gap and the bottom voice coil is positioned with no portion within the bottom air gap.

9. The loudspeaker of claim 1, wherein: ​ The top voice coil is comprised of a first wire winding wound in a first direction on a top portion of the bobbin, and the bottom voice coil is comprised of a second wire winding wound in a second direction on a bottom portion of the bobbin.

10. The loudspeaker of claim 1, wherein: The magnetic assembly further comprises an annular center portion and an annular sleeve portion, the sleeve portion concentrically surrounding the center portion, wherein there is an air gap spacing between the sleeve portion and the center portion, wherein the top air gap is a top portion of the air gap spacing and the bottom air gap is a bottom portion of the air gap spacing.

11. A loudspeaker comprising: a magnetic assembly having a first air gap and a second air gap spaced apart from each other along an axis; and a voice coil assembly comprising a bobbin having a first voice coil and a second voice coil spaced apart from each other along the axis, the bobbin movable relative to the magnetic assembly along the axis in a first direction and a second direction, wherein at least one of the voice coils is at least partially positioned within at least one of the air gaps, respectively; and wherein at an axial position of the bobbin relative to the magnetic assembly, a length of the first voice coil extending beyond the first air gap in the first direction is greater than a length of the first voice coil extending beyond the first air gap in the second direction, and a length of the second voice coil extending beyond the second air gap in the second direction is greater than a length of the second voice coil extending beyond the second air gap in the first direction.

12. The loudspeaker of claim 11, wherein: the length of the first voice coil extending beyond the first air gap in the first direction is equal to the length of the second voice coil extending beyond the second air gap in the second direction.

13. The loudspeaker of claim 11, wherein: the length of the first voice coil extending beyond the first air gap in the second direction is equal to the length of the second voice coil extending beyond the second air gap in the first direction.

14. The loudspeaker of claim 11, wherein: at another axial position of the bobbin relative to the magnetic assembly, none of the first voice coil is positioned within the first air gap, and only a portion of the second voice coil is positioned within the second air gap.

15. The loudspeaker of claim 11, wherein: at another axial position of the bobbin relative to the magnetic assembly, only a portion of the first voice coil is positioned within the first air gap, and none of the second voice coil is positioned within the second air gap.

16. A dual coil, dual gap, electromagnetic transducer for a loudspeaker, comprising: a magnetic assembly comprising an annular center portion and an annular sleeve portion concentrically surrounding the center portion with an air gap spacing between the sleeve portion and the center portion, the center portion and the sleeve portion having a common central axis extending in an axial direction, the center portion comprising a first top pole piece and a first bottom pole piece, the sleeve portion comprising a second top pole piece and a second bottom pole piece, and the top pole pieces being opposite to form a top air gap therebetween and the bottom pole pieces being opposite to form a bottom air gap therebetween, wherein the top air gap and the bottom air gap are spaced apart from each other along a second axis extending in the axial direction; a voice coil assembly comprising a bobbin having a top voice coil and a bottom voice coil spaced apart from each other along the second axis, the bobbin being movable relative to the magnetic assembly along the second axis in an upward direction and a downward direction, wherein at least one of the top voice coil and the bottom voice coil is at least partially positioned within at least one of the top air gap and the bottom air gap, respectively; and wherein the top voice coil and the bottom voice coil are spaced apart from each other along the second axis with an outward offset such that, at an average axial position of the bobbin relative to the magnetic assembly, a portion of the top voice coil extending upward above the top air gap is greater than a portion extending downward below the top air gap, and a portion of the bottom voice coil extending downward below the bottom air gap is greater than a portion extending upward above the bottom air gap.

17. The dual coil, dual gap, electromagnetic transducer of claim 16, wherein: the portion of the top voice coil extending upward above the top air gap and the portion of the bottom voice coil extending downward below the bottom air gap have the same length along the axis.

18. The dual coil, dual gap, electromagnetic transducer of claim 16, wherein: the portion of the top voice coil extending downward below the top air gap and the portion of the bottom voice coil extending upward above the bottom air gap have the same length along the axis.

19. The dual coil, dual gap, electromagnetic transducer of claim 16, wherein: the top voice coil and the bottom voice coil are spaced apart from each other along the axis with the outward offset such that, at a farthest upward axial position of the bobbin relative to the magnetic assembly, the top voice coil is not positioned within the top air gap with any portion and only a lowermost portion of the bottom voice coil is positioned within the bottom air gap.

20. The dual coil, dual gap, electromagnetic transducer of claim 16, wherein: the top voice coil and the bottom voice coil are spaced apart from each other along the axis with the outward offset such that, at a farthest downward axial position of the bobbin relative to the magnetic assembly, only an uppermost portion of the top voice coil is positioned within the top air gap and the bottom voice coil is not positioned within the bottom air gap with any portion.

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