Loudspeaker and use method thereof

Abstract

The electro-acoustic driver may be used in a speaker system that employs a driver with a magnetic negative spring (MNS). The magnets of the MNS may be arranged such that the rotatable magnetic core is rotatable in a plane perpendicular to the axis of motion of the armature of the MNS such that the magnitude of the first magnetic negative spring force and the magnitude of the second magnetic negative spring force of the MNS vary based on the rotational position of the rotatable magnetic core. The speaker may include a housing, a sound panel mechanically connected to the housing, and a magnetic negative spring having a first permanent magnet connected to the armature and a second permanent magnet rotatable relative to the first permanent magnet in response to a feedback signal.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority and benefit to U.S. Patent Application No. 63 / 505,759, filed June 2, 2023, entitled “Speaker and Method of Use Thereof,” which is jointly assigned to the assignee of this invention and is incorporated herein by reference in its entirety for all purposes.

[0003] This application is also related to International Patent Application No. PCT / US2020 / 051633 (“Pinkerton '633 PCT Application”), filed September 18, 2020, entitled “Electroacoustic Driver and Loudspeaker Including the Same” by Joseph F. Pinkerton et al., which is incorporated herein by reference in its entirety for all purposes.

[0004] This application is also related to International Patent Application No. PCT / US2022 / 041747 (“Pinkerton '747 PCT Application”), filed August 26, 2022, entitled “Speaker and Method of Use Therewith” by Joseph F. Pinkerton et al., which is incorporated herein by reference in its entirety for all purposes.

[0005] This application is also related to U.S. Patent Application Nos. 18 / 319,079 and 18 / 319,113, filed May 17, 2023, entitled “Speaker and Method of Use Thereof,” by Joseph F. Pinkerton et al. U.S. Patent Application No. 18 / 319,113 (“Pinkerton '113 Application”) is incorporated herein by reference in its entirety for all purposes. Technical Field

[0006] This invention relates to loudspeakers and methods of using them, particularly loudspeakers having a driver including a magnetic negative spring (MNS) (e.g., a repulsion-attraction driver (RAD)). Background Technology

[0007] Figure 1 shows a prior art audio force transducer 100, which includes a fixed magnetic flux path 101 (soft iron) and a sliding coil frame (also called an "armature") 103. The fixed magnetic flux path has a permanent magnet 102, and the sliding coil frame has an electric coil (also called a "voice coil") 104. The permanent magnet 102 and the electric coil 104 are separated by an air gap 105. Magnetic force will cause the coil frame 103 to slide inward and outward along the z-axis direction (as shown in Figure 1), which will cause the speaker panel (not shown) to move to produce audible sound.

[0008] As disclosed and taught in Pinkerton's '633 PCT application, large pressures acting on the soundboard can be counteracted or partially counteracted by using a magnetic negative spring (MNS) as part of a repulsive-attractive driver (RAD) (also known as a magnetoresistive driver) or a permanent magnet crown (PMC) driver.

[0009] Figure 2A (which is Figure 18D of Pinkerton '633 PCT application) shows a perspective view of some components (primarily permanent magnets) of a repulsive / attractive MNS. Figure 2B shows a perspective view of the armature used in the repulsive / attractive MNS shown in Figure 2A.

[0010] As shown in Figures 2A-2B (which provides the movement of the coil frame along the z-direction), a very wide portion of the voice coils 1815a-1815b is always immersed in the magnetic field (which makes the force generated by each unit current input approximately constant at all armature positions).

[0011] The repulsive / attractive MNS shown in Figures 2A-2B has fixed magnetic poles (e.g., fixed magnetic north poles 1801a-1804a and fixed magnetic south poles 1801b-1804b) made of permanent magnets (instead of steel), and thus moving magnets with opposite polarities on the armature (e.g., moving magnetic north poles 1805a-1806a and moving magnetic south poles 1805b-1806b) are radially repelled by the fixed magnetic poles (this provides radial stability). As shown in Figures 2A-2B, the fixed magnetic poles are permanent magnet rings (PMRs) and the moving magnetic poles are permanent magnet triangles (PMTs). Alternatively, permanent magnet arcs can be used instead of PMTs. The PMR can be an collection of arcs that, when combined, form a ring-shaped magnet structure.

[0012] When the armature is in the centered position (as shown in Figure 2C, which is Figure 18A in Pinkerton '633 PCT application), the positive z-direction PMT array (moving magnetic north pole 1806a and moving magnetic south pole 1806b) is immersed in the reverse magnetic field of the positive z-direction PMR (fixed magnetic north poles 1802a and 1804a and fixed magnetic south poles 1802b and 1804b) and is therefore radially stable.

[0013] When the armature is in a partially negative z-direction position (as shown in Figure 2D, which is Figure 18B of Pinkerton '633 PCT application), in this position, the positive z-direction PMT array (moving magnetic north pole 1806a and moving magnetic south pole 1806b) is partially immersed in the reverse magnetic field of the positive z-direction PMR (fixed magnetic north poles 1802a and 1804a and fixed magnetic south poles 1802b and 1804b) and remains radially stable. In this position, the axial / desired force is large because the positive z-direction PMT array (moving magnetic north pole 1806a and moving magnetic south pole 1806b) is repelled by the positive z-direction PMR (fixed magnetic north poles 1802a and 1804a and fixed magnetic south poles 1802b and 1804b) and attracted by the magnetic edge field of the negative z-direction PMR (fixed magnetic north poles 1801a and 1803a and fixed magnetic south poles 1801b and 1803b).

[0014] When the armature is in a completely negative z-direction position (as shown in Figure 2E, which is Figure 18C of Pinkerton '633 PCT application), the positive z-direction PMT array (moving magnetic north pole 1806a and moving magnetic south pole 1806b) is not immersed in the reverse magnetic field of the positive z-direction PMR (fixed magnetic north poles 1802a and 1804a and fixed magnetic south poles 1802b and 1804b), but is partially immersed in the magnetic edge field of the negative z-direction PMR (fixed magnetic north poles 1801a and 1803a and fixed magnetic south poles 1801b and 1803b), and this position still provides some radial stability. At the position shown in Figure 18C, the axial / desired force is also large because the positive z-direction PMT array is repelled by the magnetic edge field of the positive z-direction PMR and attracted by the negative z-direction PMR.

[0015] Due to symmetry, the same stability is provided when the armature moves along the positive z-direction.

[0016] This provides a radial stabilizing force that helps to keep the armature centered in the air gap between the inner and outer permanent magnet rings.

[0017] Figure 3 (which is Figure 20 of Pinkerton '633 PCT application) shows a loudspeaker 2000 in which an MNS (e.g., as shown in Figures 2A-2B) can be used. The loudspeaker 2000 has a sealed chamber (or sealed housing) 2001 and a movable panel 2002 (attached to a flexible "surrounding" element 2005, for example made of rubber, to allow the movable panel 2002 to move along the positive and negative z-directions). The loudspeaker 2000 also includes an MNS 2003 and a voice coil 2004, the MNS and the voice coil being positioned to allow the movable panel 2002 to move along the positive and negative z-directions. The loudspeaker 2000 also includes a sensor 2006 (e.g., a position and / or velocity sensor, which may be optical or inductive), which provides position or velocity feedback to control circuitry. In the orientation of Figure 3 (shown by the xz axis shown in the figure, where the y-direction is perpendicular to the xz axis), the movable sound panel 2002 moves outward and inward in the z-direction due to the movement of the armature along the z-direction. This movement is caused by the magnetic force generated by it.

[0018] When the sound panel is in its neutral / relaxed position, no force acts on the movable sound panel 2002. When the movable sound panel 2002 moves along the positive z-direction, this creates a partial vacuum (i.e., a pressure decrease) within the sealed chamber 2001. When the movable sound panel 2002 moves along the negative z-direction, this creates an increased pressure within the sealed chamber 2001. Therefore, this movement generates additional force due to the pressure decrease / increase. Summary of the Invention

[0019] This invention relates to loudspeakers and methods of using them, and particularly to loudspeakers having a driver including a magnetic negative spring (MNS) (e.g., a repulsion-attraction driver (RAD) and a permanent magnet crown (PMC) driver).

[0020] In summary, in one aspect, the present invention features a loudspeaker. The loudspeaker includes a housing. The loudspeaker also includes a sound panel mechanically connected to the housing. The loudspeaker further includes a movable armature mechanically connected to the sound panel, the movable armature including a voice coil. The movable armature is operable to move the sound panel along a first axis toward the housing to generate a first pneumatic force, and to move the sound panel away from the housing along the first axis to generate a second pneumatic force. The loudspeaker also includes a magnetic negative spring having: a first magnetic negative spring portion mechanically connected to the movable armature; and a second magnetic negative spring portion fixed relative to the housing along the first axis. The magnetic negative spring is operable to provide a first magnetic negative spring force when the sound panel moves along the first axis toward the housing and to provide a second magnetic negative spring force when the sound panel moves away from the housing along the first axis. The first magnetic negative spring force is opposite in direction to the first pneumatic force. The second magnetic negative spring force is opposite in direction to the second pneumatic force. The first magnetic negative spring portion includes a first armature magnet. The second magnetic negative spring portion includes a rotatable magnetic core that is rotatable in a plane perpendicular to the first axis, such that the magnitudes of the first and second magnetic negative spring forces vary based on the rotational position of the rotatable magnetic core.

[0021] Embodiments of the present invention may include one or more of the following features:

[0022] When the rotatable magnetic core rotates to the first position, the magnitudes of the first and second magnetic negative spring forces reach their maximum. When the rotatable magnetic core rotates to the second position, the magnitudes of the first and second magnetic negative spring forces reach their minimum. The rotatable magnetic core can rotate to any position between the first and second positions.

[0023] The minimum value of the first magnetic negative spring force and the minimum value of the second magnetic negative spring force can be less than 20% of the maximum value of the first magnetic negative spring force and the maximum value of the second magnetic negative spring force.

[0024] The minimum value of the first magnetic negative spring force and the minimum value of the second magnetic negative spring force can be less than 10% of the maximum value of the first magnetic negative spring force and the maximum value of the second magnetic negative spring force.

[0025] The maximum magnitude of the first magnetic negative spring force and the maximum magnitude of the second magnetic negative spring force can be peak forces exceeding 50 Newtons.

[0026] The maximum magnitude of the first magnetic negative spring force and the maximum magnitude of the second magnetic negative spring force can be peak forces exceeding 100 Newtons.

[0027] The maximum magnitude of the first magnetic negative spring force and the maximum magnitude of the second magnetic negative spring force can be peak forces exceeding 200 Newtons.

[0028] The rotatable magnetic core can be operated to rotate in response to a feedback sensor.

[0029] The feedback signal can originate from a pressure sensor.

[0030] The feedback signal can be derived from the voice coil resonant frequency algorithm.

[0031] Feedback signals can originate from song files.

[0032] The algorithm can scan the song file to identify the main low-frequency note and instruct the rotatable core to rotate to a position where the voice coil resonant frequency is close to that of the main low-frequency note.

[0033] The rotatable magnetic core can rotate only when music is playing.

[0034] The speaker may also include a position sensor that senses the position of the sound panel. Feedback signals may originate from this position sensor.

[0035] The position sensor can be an infrared position sensor.

[0036] The rotatable magnetic core can be rotated by a rotating system including a motor.

[0037] The motor can be an electric motor.

[0038] The rotating system may also include pulleys and / or gears.

[0039] The rotatable magnetic core may include a closed magnetic circuit comprising a first annular magnet and a second annular magnet. The first annular magnet may include a plurality of first annular arc segment magnets, which are circumferentially positioned in a plane perpendicular to a first axis and circumferentially separated by a gap between the first annular arc segments. Each of the first annular arc segment magnets may include an inner first annular arc segment magnet and an outer first annular arc segment magnet. The inner first annular arc segment magnet may have a smaller radius than the outer first annular arc segment magnet. The second annular magnet may include a plurality of second annular arc segment magnets, which are circumferentially positioned in a plane perpendicular to the first axis and circumferentially separated by a gap between the second annular arc segments. Each of the second annular arc segment magnets may include an inner second annular arc segment magnet and an outer second annular arc segment magnet. The inner second annular arc segment magnet may have a smaller radius than the outer second annular arc segment magnet.

[0040] Each of the first annular arc segment magnets may have the same arc length as each of the second annular arc segment magnets.

[0041] Each of the first annular arc segment gaps can have the same arc length as each of the second annular arc segment gaps.

[0042] The ratio of the arc length of the first annular arc segment magnet to the arc length of the gap in the first annular arc segment can be in the range of 1:1 and 2:1.

[0043] The arc length of each segment in the first annular arc magnet can be 60°.

[0044] The arc length of each segment in the first annular arc gap can be 30°.

[0045] The arc length of each segment in the first annular arc magnet can be 45°.

[0046] The arc length of each segment in the first annular arc gap can be 45°.

[0047] The arc length of each segment in the first annular arc magnet can be x, where 45°≤x≤60°.

[0048] The arc length of each segment in the first annular arc gap can be 90°-x.

[0049] The first annular magnet may include exactly four first annular arc segment magnets and exactly four first annular arc segment gaps. The second annular magnet may include exactly four second annular arc segment magnets and exactly four second annular arc segment gaps.

[0050] The voice coil and the magnetic negative spring can share the same magnetic circuit.

[0051] In summary, in another aspect, the invention is characterized by a method. The method includes selecting any of the aforementioned loudspeakers. The method further includes rotating a rotatable magnetic core in a plane perpendicular to a first axis, such that the magnitudes of a first magnetic negative spring force and a second magnetic negative spring force change. The method also includes operating the loudspeaker to produce audible sound.

[0052] In summary, in another aspect, the invention is characterized by a loudspeaker. The loudspeaker includes a housing. The loudspeaker also includes a sound panel mechanically connected to the housing. The loudspeaker further includes a magnetic negative spring having a first permanent magnet connected to an armature and a second permanent magnet capable of rotating relative to the first permanent magnet in response to a feedback signal.

[0053] Embodiments of the present invention may include one or more of the following features:

[0054] The first permanent magnet may include multiple first arc segments. The second permanent magnet may include multiple second arc segments.

[0055] The feedback signal can be a song file.

[0056] In summary, in another aspect, the invention is characterized by a method. The method includes selecting any of the aforementioned loudspeakers. The method further includes rotating a second permanent magnet relative to a first permanent magnet in response to a feedback signal. The method further includes operating the loudspeaker to produce audible sound. Attached Figure Description

[0057] Figure 1 (Figure 1 of Pinkerton '633 PCT application) is a schematic cross-sectional view of a prior art audio force transducer.

[0058] Figure 2A (Figure 18D of Pinkerton '633 PCT application) is a schematic perspective view showing some components (mainly permanent magnets) of a prior art repulsive / attractive MNS (as shown in Figures 2C-2E).

[0059] Figure 2B is a schematic perspective view of the armature used in the prior art repulsive / attractive MNS shown in Figure 2A.

[0060] Figures 2C-2E (Figures 18A-18C of Pinkerton '633 PCT application, respectively) are schematic cross-sectional views of embodiments of prior art repulsive / attractive MNS, wherein the voice coil armature is in different positions (centered, partially in the negative z direction, and completely in the negative z direction, respectively).

[0061] Figure 3 (Figure 20 of Pinkerton '633 PCT application (where the orientation of the z-axis is changed)) is a schematic diagram of a loudspeaker in which an MNS can be used (e.g., as shown in Figure 2A).

[0062] Figure 4 This is a diagram of the repulsive / attractive MNS at the location of maximum RAD force.

[0063] Figures 5A-5B This is a diagram (at different angles) of a repulsive / attractive MNS at the location of minimum RAD force.

[0064] Figures 6A-6B This is an illustration of an embodiment with a motor and pulley (or gear) that can rotate the core of a repulsive / attractive MNS.

[0065] Figure 7 It is a graph showing the power versus frequency relationship of a 6mm voice coil (28AWG and 30AWG).

[0066] Figures 8A-8B This is a schematic diagram of another repulsive / attractive MNS at the positions of maximum and minimum RAD force, respectively. Detailed Implementation

[0067] This invention relates to loudspeakers and methods of using them, particularly loudspeakers having drivers including magnetic negative springs (MNS) (e.g., repulsion-attraction drivers (RAD) and permanent magnet crown (PMC) drivers).

[0068] It has been found that by rotating the magnetic core relative to the armature, the RAD force can be varied by more than five times (compared to approximately 1.1 times for the movable steel plunger mechanism described in Pinkerton '113 application). Since the RAD force can be essentially shut off (reduced to less than 20% of its maximum force), an actuation mechanism (e.g., pumps and valves) can be eliminated. That is, the speaker can be started instantaneously with the RAD force nearly off, and then the RAD force can be increased as needed.

[0069] Figure 4 An embodiment is shown in the position of maximum RAD force (rotation angle = 0°). The outer stator magnets 401a-401b and the inner stator magnets 402a-402b occupy 60° (instead of 90°), and there is a 30° air space 405 between the 60° stator magnet arcs. Figure 4 As shown, the span of the outer stator magnets 401a-401b and the inner stator magnets 402a-402b intersecting the 0° line (extending along the positive "x" direction) is from -30° to +30°.

[0070] The armature magnets 403a-403b, which repel (outer stator magnets 401a-401b and inner stator magnets 402a-402b), are completely immersed in the stator magnetic field, while the armature magnets that attract (e.g., armature magnets 404a-404b) are located outside the stator magnetic field. At this maximum force position, the behavior of the RAD is very similar to that disclosed and taught in Pinkerton '113 application.

[0071] exist Figure 4 In the orientation, the view is located in the xy plane and perpendicular to the z direction. The armature of the RAD (and the armature magnets 403a-403b and 404a-404b) moves in the z direction.

[0072] Figures 5A-5B The location of minimum RAD force is shown (rotation angle = 30°). At this location, half of the repulsive armature magnets 403a-403b are outside the stator magnetic field, while the attractive armature magnets 404a-404b are completely immersed in the stator magnetic field. Because the two types of armature magnets (repulsive armature magnets 403a-403b and attractive armature magnets 404a-404b) generate axial forces in opposite directions (and each is equally immersed in the stator magnetic field), the RAD force is less than 20% of its maximum value. Figure 4 Similarly, in Figure 5A In the orientation, the view is located in the xy plane and perpendicular to the z direction. Figure 5B A perspective view of the angular RAD at its position of minimum force (rotation angle = 30°) is shown, as follows. Figure 5B As shown.

[0073] The RAD force position can be moved between the maximum RAD force position (rotation angle = 0°) and the minimum RAD force position (rotation angle = 30°). For example, it can be used as follows: Figure 6A The motor 601 and pulley 602 (or gear) shown cause the magnetic core (with outer stator magnets 401a-401b and inner stator magnets 402a-402b) to rotate in the xy plane relative to the armature (with repulsive armature magnets 403a-403b and attractive armature magnets 404a-404b). A strong axial spring and axial bearing can be used to always apply an axial force of about 1000 Newtons to the magnetic core (so that the magnetic core does not move axially when subjected to a RAD force of about + / - 200 Newtons).

[0074] like Figure 4 and Figures 5A-5B As shown, the outer stator magnets 401a-401b and the inner stator magnets 402a-402b each have a stator magnet arc of 60°. Therefore, the four sets of outer and inner stator magnets occupy a total of 240° of a 360° circle, and the four gaps 405 each have an arc length of 30°. This means that for... Figure 4 and Figures 5A-5B In each gap 405, 30° of stator magnet material is removed between the 60° stator magnet arcs. This can be used to increase the radial thickness of the outer stator magnets 401a-401b (e.g., Figure 4 and Figures 5A-5B (As shown). This allows for increasing the radial air gap between the inner and outer stator magnets, or strengthening the magnetic field, or both. This makes the maximum RAD force (because the armature magnet can have a greater radial thickness with a larger radial air gap) roughly the same as a conventional RAD without a circumferential gap between the stator magnets. The radial thickness of the voice coil (located on the armature) can also be greater, and therefore have lower resistance, to help compensate for the fact that part of it is located outside the stator magnetic field (so its electrical efficiency can be roughly the same as a conventional RAD voice coil).

[0075] This allows the magnetic core to be rotated only a few degrees to compensate for significant changes in altitude (and the resulting air pressure), manufacturing deviations, and changes in the stiffness of the centering support suspension over time. Another significant advantage is a substantial increase in efficiency, as the RAD resonant frequency can be rapidly adjusted within the 30Hz-60Hz range, matching the frequency of one or more main low-frequency notes in a given song to the RAD resonant frequency, thereby reducing power consumption by an order of magnitude. Figure 7 As shown. Figure 7 The power-frequency relationship of a 6mm voice coil (28AWG and 30AWG, corresponding to curves 701 and 702, respectively) is shown.

[0076] Figures 8A-8B Different embodiments of the invention are shown, employing a 45° stator magnet arc and a 45° gap 805 between the stator magnets. Specifically, the outer stator magnets 801a-801b and the inner stator magnets 802a-802b have a 45° stator magnet arc (with...). Figure 4 and Figures 5A-5B The 60° stator magnet arc shown is opposite to the other side. The gap 805 is 45° (with...). Figure 4 and Figures 5A-5B (The 30° gap shown is relative). Figure 4 and Figure 5A Similarly, in Figures 8A-8B In the orientation, the view is located in the xy plane and perpendicular to the z direction. The armature (and armature magnets 803a-803b) of the RAD moves in the z direction.

[0077] Figure 8A The image shows the MNS at the position of maximum RAD force (rotation angle = 0°). Figure 8B The MNS is shown in the position of minimum RAD force (rotation angle = 45°). The maximum / minimum force ratio of this device is over 10 times (higher than...). Figure 4 and Figures 5A-5B (More than 5 times that of the illustrated embodiment). However, Figures 8A-8B The 45° rotation embodiment shown results in half of the voice coil being outside the stator magnetic field, thus requiring twice the current to generate a given axial force. Even if the voice coil resistance could be halved (due to the increased radial thickness of the voice coil), it would still consume twice the power to generate a given force compared to a conventional RAD voice coil.

[0078] therefore, Figure 4 and Figures 5A-5B The illustrated embodiment has the following advantages: 67% of the voice coil is immersed in the stator magnetic field, therefore it requires only 1.5 times the current (compared to a conventional RAD) for a given force. If the voice coil's resistance is halved (due to its radial thickness being doubled), it will consume only 1.1 times more power compared to a conventional RAD voice coil.

[0079] While embodiments of the invention have been shown and described, those skilled in the art can modify them without departing from the spirit and teachings of the invention. The embodiments and examples described herein are exemplary only and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are all within the scope of the invention. Therefore, other embodiments are also within the scope of the following claims. The scope of protection is not limited by the foregoing description, but only by the following claims, which include all equivalents of the subject matter of the claims.

[0080] All patents, patent applications and publications cited in this document are incorporated herein by reference in their entirety, to the extent that they provide illustrative, procedural or other details to the content set forth herein.

[0081] Quantities and other numerical data may be presented in range format herein. It should be understood that this range format is for convenience and brevity only and should be interpreted flexibly, including not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges contained within that range, as if each value and subrange had been explicitly stated. For example, a range of values ​​from approximately 1 to approximately 4.5 should be interpreted as including not only the explicitly stated limits of 1 to approximately 4.5, but also individual values ​​such as 2, 3, and 4, and subranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges containing only a single value, such as "less than approximately 4.5," which should be interpreted as including all values ​​and ranges stated above. Furthermore, this interpretation should apply regardless of the breadth of the range or the characteristics described.

[0082] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While any similar or equivalent methods, apparatuses, and materials described herein may be used to practice or test the subject matter of this disclosure, representative methods, apparatuses, and materials are described here.

[0083] Following long-standing patent law practice, the terms “a” and “an” are used in this application (including the claims) to mean “one or more”.

[0084] Unless otherwise stated, all figures used in this specification and claims to indicate quantities of components, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in this specification and appended claims are approximate values ​​and may vary depending on the characteristics sought to be obtained from the subject matter of this disclosure.

[0085] As used herein, the terms “about” and “substantially” when referring to numerical values ​​or quantities, weights, times, volumes, concentrations, or percentages mean to cover variations of ±20%, ±10%, ±5%, ±1%, ±0.5%, and ±0.1% from the specified amount in some embodiments, as such variations are suitable for implementing the disclosed method.

[0086] As used herein, the terms “substantially vertical” and “substantially parallel” mean to cover variations of ±10° from the vertical and parallel directions respectively in some embodiments, ±5° from the vertical and parallel directions respectively in some embodiments, ±1° from the vertical and parallel directions respectively in some embodiments, and ±0.5° from the vertical and parallel directions respectively in some embodiments.

[0087] As used herein, the term “and / or” in the context of an enumeration of entities means that these entities exist individually or in combination. Thus, for example, the phrase “A, B, C and / or D” includes not only the individual entities A, B, C, and D, but also any and all combinations and subcombinations of A, B, C, and D.

Claims

1. A loudspeaker comprising: (a) a housing; (b) a sound panel mechanically connected to the housing; (c) a movable armature mechanically connected to the sound panel, the movable armature comprising a voice coil, wherein the movable armature is operable to move the sound panel along a first axis toward the housing to produce a first gas pressure force and to move the sound panel along the first axis away from the housing to produce a second gas pressure force; and (d) a magnetic negative spring having a first magnetic negative spring portion mechanically connected to the movable armature and a second magnetic negative spring portion held stationary relative to the housing along the first axis, wherein (i) the magnetic negative spring is operable to provide a first magnetic negative spring force when the sound panel is moved along the first axis toward the housing and a second magnetic negative spring force when the sound panel is moved along the first axis away from the housing; (ii) the first magnetic negative spring force is opposite in direction to the first gas pressure force; (iii) the second magnetic negative spring force is opposite in direction to the second gas pressure force; (iv) the first magnetic negative spring portion comprises a first armature magnet; and (v) the second magnetic negative spring portion comprises a rotatable magnetic core that is rotatable within a plane perpendicular to the first axis such that a magnitude of the first magnetic negative spring force and a magnitude of the second magnetic negative spring force vary based on a rotational position of the rotatable magnetic core.

2. The loudspeaker of claim 1, wherein (a) the magnitude of the first magnetic negative spring force and the magnitude of the second magnetic negative spring force reach a maximum when the rotatable magnetic core is rotated to a first position; (b) the magnitude of the first magnetic negative spring force and the magnitude of the second magnetic negative spring force reach a minimum when the rotatable magnetic core is rotated to a second position; and (c) the rotatable magnetic core is rotatable to any position between the first position and the second position. The minimum magnitude of the first magnetic negative spring force and the second magnetic negative spring force is less than 20% of the maximum magnitude of the first magnetic negative spring force and the second magnetic negative spring force.

3. The loudspeaker of claim 2, wherein, The minimum magnitude of the first magnetic negative spring force and the second magnetic negative spring force is less than 10% of the maximum magnitude of the first magnetic negative spring force and the second magnetic negative spring force.

4. The loudspeaker of claim 2, wherein, The maximum magnitude of the first magnetic negative spring force and the second magnetic negative spring force is a peak force that exceeds 50 Newtons.

5. The loudspeaker of claim 2, wherein, The maximum magnitude of the first magnetic negative spring force and the second magnetic negative spring force is a peak force that exceeds 100 Newtons.

6. The loudspeaker of claim 2, wherein, The maximum magnitude of the first magnetic negative spring force and the second magnetic negative spring force is a peak force that exceeds 200 Newtons.

7. The loudspeaker of claim 2, wherein, The rotatable magnetic core is operable to rotate in response to a feedback sensor.

8. The loudspeaker of claim 2, wherein, The feedback signal originates from a pressure sensor.

9. The loudspeaker of claim 8, wherein, The feedback signal originates from a voice coil resonant frequency algorithm.

10. The loudspeaker of claim 8, wherein, The feedback signal originates from a song file.

11. The loudspeaker of claim 8, wherein, ​ 12. The loudspeaker of claim 11, wherein, An algorithm scans the song file to determine a dominant low frequency note and instructs the rotatable magnetic core to rotate to a position that brings the voice coil resonant frequency close to the frequency of the dominant low frequency note.

13. The loudspeaker of claim 11, wherein, The rotatable magnetic core only rotates when music is playing.

14. The speaker of claim 8, wherein, (a) the speaker further comprises a position sensor that senses a position of the sound panel; and (b) the feedback signal originates from the position sensor.

15. The loudspeaker of claim 14, wherein, The position sensor is an infrared position sensor.

16. The loudspeaker of claim 1, wherein, The rotatable magnetic core is rotated by a rotation system that includes a motor.

17. The loudspeaker of claim 16, wherein, The motor is an electric motor.

18. The loudspeaker of claim 16, wherein, The rotation system further comprises a pulley and / or a gear.

19. The speaker of claim 1, wherein, (a) the rotatable magnetic core comprises a closed magnetic circuit that includes a first ring magnet and a second ring magnet; (b) the first ring magnet comprises a plurality of first ring arc segment magnets that are positioned circumferentially in a plane that is perpendicular to the first axis and are separated circumferentially by first ring arc segment gaps; (c) each of the first ring arc segment magnets comprises an inner first ring arc segment magnet and an outer first ring arc segment magnet, wherein a radius of the inner first ring arc segment magnet is less than a radius of the outer first ring arc segment magnet; (d) the second ring magnet comprises a plurality of second ring arc segment magnets that are positioned circumferentially in a plane that is perpendicular to the first axis and are separated circumferentially by second ring arc segment gaps; and (e) each of the second ring arc segment magnets comprises an inner second ring arc segment magnet and an outer second ring arc segment magnet, wherein a radius of the inner second ring arc segment magnet is less than a radius of the outer second ring arc segment magnet.

20. The loudspeaker of claim 19, wherein, An arc length of each of the first ring arc segment magnets is the same as an arc length of each of the second ring arc segment magnets.

21. The loudspeaker of claim 20, wherein, An arc length of each of the first ring arc segment gaps is the same as an arc length of each of the second ring arc segment gaps.

22. The loudspeaker of claim 21, wherein, A ratio of the arc length of the first ring arc segment magnets to the arc length of the first ring arc segment gaps is in a range between 1 : 1 and 2:

1.

23. The loudspeaker of claim 21, wherein, The arc length of each of the first ring arc segment magnets is 60°.

24. The loudspeaker of claim 23, wherein, The arc length of each of the first ring arc segment gaps is 30°.

25. The loudspeaker of claim 21, wherein, The arc length of each of the first ring arc segment magnets is 45°.

26. The loudspeaker of claim 25, wherein, The arc length of each of the first ring arc segment gaps is 45°.

27. The loudspeaker of claim 21, wherein, The arc length of each of the first ring arc segment magnets is x, where 45° < x < 60°.

28. The loudspeaker of claim 27, wherein, The arc length of each of the first ring arc segment gaps is 90° - x.

29. The speaker of claim 19, wherein, (a) the first ring magnet comprises exactly four first ring arc segment magnets and exactly four first ring arc segment gaps; and (b) the second ring magnet comprises exactly four second ring arc segment magnets and exactly four second ring arc segment gaps.

30. The loudspeaker of claim 1, wherein, The voice coil and the magnetic negative spring share the same magnetic circuit.

31. A method comprising: (a) selecting a loudspeaker according to any of claims 1-30; (b) causing the rotatable magnetic core to rotate in a plane perpendicular to the first axis, such that the magnitude of the first magnetic negative spring force and the second magnetic negative spring force changes; and (c) operating the loudspeaker to produce audible sound.

32. A loudspeaker comprising: (a) an enclosure; (b) a sound panel mechanically connected to the enclosure; and (c) a magnetic negative spring having a first permanent magnet connected to an armature and a second permanent magnet rotatable relative to the first permanent magnet in response to a feedback signal.

33. The loudspeaker of claim 32, wherein (a) the first permanent magnet comprises a plurality of first arc segments; and (b) the second permanent magnet comprises a plurality of second arc segments.

34. The loudspeaker of claim 32, wherein, The feedback signal is a song file.

35. A method comprising: (a) selecting a loudspeaker according to any of claims 32-34; (b) causing the second permanent magnet to rotate relative to the first permanent magnet in response to the feedback signal; and (c) operating the loudspeaker to produce audible sound.

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