Speaker with inertial exciter comprising a magnet assembly suspended from a mounting frame

Abstract

A loudspeaker comprising: a mounting frame; an acoustic radiator; a drive unit. The drive unit comprises: a magnet assembly comprising a magnet unit configured to provide a magnetic field in an air gap; a voice coil assembly; and at least one drive unit suspension. The voice coil assembly comprises: an attachment providing attachment between the voice coil assembly and the acoustic radiator; a voice coil; a voice coil former extending from the attachment into the air gap, wherein the voice coil is mounted to the voice coil former such that the voice coil is located in the air gap when the drive unit is at rest; and a tubular member located radially outward of the voice coil former relative to an axis of motion and overlapping the voice coil former along at least a portion of the axis of motion. The at least one drive unit suspension is attached to the tubular member and to a portion of the magnet assembly located radially outward of the tubular member, such that the acoustic radiator is suspended from the magnet assembly via the voice coil assembly by the at least one drive unit suspension. The magnet unit assembly is suspended from the mounting frame by at least one mounting frame suspension.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to GB2009203.7, filed on June 17, 2020. Technical Field

[0003] This invention relates to a loudspeaker, which includes a driving unit. A corresponding method is also disclosed. Background Technology

[0004] Figure 1(a) illustrates an example of a conventional loudspeaker, which typically includes a sound radiator (often referred to as a diaphragm) suspended from a magnet assembly comprising a frame mounted in a soundproof panel or loudspeaker enclosure. Sound is generated by the movement of the diaphragm, which is actuated by a voice coil attached to the diaphragm and interacts with a magnet unit that is part of the magnet assembly, which includes the frame. The soundproof panel or loudspeaker enclosure is used to suppress the cancellation between the sounds generated by the front and back of the diaphragm.

[0005] Figure 1(b) shows an example of an inertial exciter, which is typically a device with a magnet assembly configured to suspend from a sound radiator such as a panel or soundboard, and these devices are configured to apply an inertial force to the sound radiator so that the sound radiator vibrates to produce sound. Inertial exciters are commonly used in automotive, aerospace, and consumer products.

[0006] Loudspeakers incorporating inertial exciters are well known, and examples are disclosed, for example, in Examples [1] through

[12] .

[0007] An inertial exciter can transfer a wide bandwidth of mechanical vibrational energy to a sound radiator (usually a panel or wall) that is configured to sustain that vibrational energy across its entire surface to produce sound output. For a loudspeaker incorporating an inertial exciter, the spectrum of interest (the spectrum of sound the loudspeaker can produce) can be the audible range (20 Hz to 20 kHz).

[0008] To generate sound over a wide bandwidth, inertial exciters typically require a low-mass, very stiff voice coil assembly (the part of the inertial exciter that includes the voice coil) to maximize efficiency within the audio bandwidth. The magnet assembly (the part of the inertial exciter that includes the magnet system), on the other hand, can have a much higher mass (and often actually does).

[0009] When mechanically fixing an inertial exciter to an acoustic panel, special attention should be paid to the following: when you want to use moving coil (MC) excitation in combination with moving magnet (MM) excitation (these types of excitation will be discussed in more detail below), ideally, the exciter is mounted to the acoustic radiator only via a coupler, that is, the magnet assembly is suspended from the acoustic radiator via the voice coil assembly, thus allowing the magnet assembly to suspend freely.

[0010] Figure 2(a) shows a loudspeaker 1 incorporating a wide-bandwidth inertial exciter that implements principles derived from the prior art. Figure 2(b) is a graph showing the force level of the loudspeaker shown in Figure 2(a) relative to frequency.

[0011] In this example, the magnet assembly 2, including the magnet unit 10 and the frame 12, is suspended from the acoustic radiator 90 via a voice coil assembly, which includes a voice coil 30 and a voice coil frame 32. When the exciter 1 is at rest, the voice coil 30 is located in the air gap 16 of the magnet unit 10.

[0012] The voice coil generates a force F according to the following equation:

[0013] F = BLI

[0014] Where B is the magnetic field, L is the length of the conductor, and I is the current (in standard units).

[0015] The inertia of magnet assembly 2 (which is typically much heavier than voice coil assembly 4) allows voice coil assembly 4 to transfer vibrational energy to acoustic radiator 90. The excitation of acoustic radiator 90 caused by the movement of the voice coil assembly is referred to herein as "moving coil" or "MC" excitation.

[0016] When the magnet assembly 2 is suspended from the acoustic radiator 90 via the voice coil assembly 4 (as in the example shown in Figure 2(a)), the resonance of the magnet assembly 2 can provide additional vibrational energy to the acoustic radiator 90 near its resonant frequency. The resonant frequency of the magnet assembly 2 is defined by the mass of the magnet assembly 2 and the flexibility of the suspension 60 from which it is suspended. The excitation of the acoustic radiator 90 caused by the resonance of the magnet assembly 2 is referred to herein as "moving magnet" or "MM" excitation.

[0017] As shown in Figure 2(b), MM excitation provides a force boost at low frequencies (labeled “MM” in Figure 2(b)), which is an advantage of systems where the exciter is mounted to the acoustic radiator only via a coupler, as illustrated in the example in Figure 2(a).

[0018] The force level provided by the MC excitation is increased by a lightweight and very stiff voice coil (labeled "MC" in Figure 2(b)).

[0019] The inventors have noticed a problem with the speaker shown in Figure 2(a). Figure 2(c) illustrates this problem.

[0020] In detail, when an acoustic panel 90 (on which a wideband inertial exciter 1 is attached) is vertically mounted, for example, in an interior door panel of a car, gravity on the magnet assembly 2 tends to cause its position to rotate relative to the voice coil assembly 4 over time. This is due to the flexibility of the individual suspension 60 (in this case, the speaker support ring), which is configured to position the voice coil 30 in the air gap 16 (and does this very well), but is not configured to suppress the rotation of the magnet assembly 2 relative to the voice coil assembly 4 in the case of a vertically mounted acoustic radiator 90 (e.g., in a door).

[0021] Existing technologies have taught several possible solutions to this problem, some of which are summarized below:

[0022] ·like Figure 3 (a)(i) and Figure 3 Scheme A (“Free Magnet System”) shown in (a)(ii)

[0023] -MC&MM work well; MC has minimal additional mass; similar to [1];

[0024] - Problem: As shown in Figure 2(c), the mass of the motor on a single suspension makes it unstable in terms of buckling.

[0025] ·like Figure 3 (b)(i) and Figure 3 Scheme B (“Grounding Magnet System”) shown in (b)(ii)

[0026] - The magnet system is stable; similar to

[13] and classic loudspeakers;

[0027] - Problem: The support frame for large panels is very large, lacks the advantages of MM excitation, and is not an inertial exciter design.

[0028] ·like Figure 3 (c)(i) and Figure 3 Scheme C (“panel bracket”) shown in (c)(ii)

[0029] - The magnet system is stable; similar to [6], [7],

[11] and

[12] ;

[0030] - Problem: Due to the influence of panel acoustics, it lacks the advantages of MM (Multi-Modal).

[0031] ·like Figure 3 (d)(i) and Figure 3 Scheme D (“Central Suspension Motor”) shown in (d)(ii)

[0032] - It has MC and MM excitation; it is quite stable; similar to [4]

[0033] - Problem: MC operation requires additional mass; the fracture of a large coupler can cause a step change in force distribution.

[0034] ·like Figure 3 (e)(i) and Figure 3 Scheme E (“Dual Suspension Motor”) shown in (e)(ii)

[0035] - Features MC and MM excitation; motor suspension provides stability; similar to [8], [9] and

[10]

[0036] - Problem: MC operation requires additional mass; the fracture of a large coupler can cause a step change in force distribution.

[0037] ·like Figure 3 (f)(i) and Figure 3 Scheme F (“Oscillator”) shown in (f)(ii)

[0038] - Only MM operates (used as an oscillator); motor suspension is stable.

[0039] Problem: Lack of sufficient bandwidth

[0040] Option F employs an inertial exciter as the vibrator, transmitting a relatively narrow bandwidth of mechanical vibrational energy to structures such as car or movie theater seats to enhance the experience through tactile stimulation. Generally, the frequency spectrum providing this enjoyment is very limited, for example, 30Hz to 80Hz. Compared to acoustic exciters, the design of the vibrator is less complex because it relies solely on the inertial vibrational energy of the moving magnet system (MM) due to its limited range of transmitting low-frequency vibrations. Mounting such a vibrator to a panel is also less critical, and heavier structures can be incorporated without compromising performance. Of course, a wide-bandwidth inertial exciter (with the free-suspension magnet system found in options A, D, and E) can also be used as the vibrator independently.

[0041] The inventors have noted that it is difficult to fabricate an inertial exciter that can successfully suppress rotation of the magnet assembly relative to the voice coil assembly while simultaneously allowing MM excitation without significantly increasing the weight of the voice coil assembly. Therefore, when the sound radiator is vertically mounted (as may be in a car door), it is difficult to fabricate an inertial exciter that provides good sound reproduction over a wide bandwidth without encountering rotational problems.

[0042]

[14] discloses a dipole loudspeaker for generating bass frequency sound. In some examples, the frame from which the diaphragm is suspended is a first frame, wherein the diaphragm is suspended from the first frame via one or more first suspensions, and wherein the first frame is suspended from the second frame via one or more second suspensions. This arrangement may help reduce vibrations transmitted from the loudspeaker to the environment.

[0043] The inventors have noticed a need for a smaller drive unit that can provide stable piston-like motion of the sound radiator without the problems caused by the swaying of the sound radiator when the speaker is in use.

[0044] In view of the above considerations, the present invention was conceived. Summary of the Invention

[0045] The first aspect of the present invention provides:

[0046] Speakers, including:

[0047] Mounting framework;

[0048] Acoustic radiator;

[0049] The drive unit includes:

[0050] A magnet assembly includes a magnet unit configured to provide a magnetic field in an air gap, wherein the air gap extends about the axis of motion of an inertial exciter.

[0051] Voice coil assembly, including:

[0052] An attachment portion that provides attachment between the voice coil assembly and the acoustic radiator;

[0053] Voice coil;

[0054] A voice coil holder that extends from the attachment into the air gap, wherein the voice coil is mounted to the voice coil holder such that the voice coil is located in the air gap when the drive unit is at rest;

[0055] A tubular member located radially outside the voice coil frame relative to the axis of motion, and overlapping the voice coil frame along at least a portion of the axis of motion;

[0056] At least one drive unit suspension is attached to the radially outer portion of the tubular member and the magnet assembly, such that the acoustic radiator is suspended from the magnet assembly via the voice coil assembly through at least one drive unit suspension.

[0057] The magnet unit assembly is suspended from the mounting frame by at least one mounting frame suspension.

[0058] In the context of this application, the term "mounting frame" is intended only to distinguish a frame from which a magnet unit assembly is suspended (by at least one mounting frame suspension) from other frames disclosed herein (e.g., "magnet assembly frame" as described below).

[0059] In the context of this application, the terms "drive unit" in "drive unit suspension" and "mounting frame" in "mounting frame suspension" are intended only to distinguish the suspension used to suspend the acoustic radiator from the magnet assembly ("drive unit suspension") from the suspension used to suspend the magnet unit assembly from the mounting frame ("mounting frame suspension").

[0060] By positioning itself radially outside the voice coil frame (preferably also including an air gap) relative to the axis of motion, the tubular member facilitates the attachment of at least one drive unit suspension (preferably two drive unit suspensions) to the portion of the magnet assembly located radially outside the tubular member.

[0061] This is advantageous because it helps to achieve stable piston-like movement of the sound radiator and reduce the swaying of the sound radiator when the speaker is in use.

[0062] By suspending the magnet unit assembly from the mounting frame, vibrations transmitted from the speaker to the environment can be reduced, for example, in a manner similar to that described in

[14] .

[0063] The axis of motion can be defined as such that when the drive unit is triggered by supplying a current carrying an audio signal to the voice coil, the voice coil assembly is configured to move relative to the magnet assembly along this axis.

[0064] When no current is supplied to the voice coil, the drive unit can be considered to be at rest.

[0065] It should be noted that in order to suspend the acoustic radiator from the magnet assembly via the voice coil assembly, the magnet assembly should be attached to the acoustic radiator only via the voice coil assembly, that is, there is no rigid attachment between the magnet assembly and the acoustic radiator.

[0066] Preferably, the drive unit includes:

[0067] The first drive unit suspension is attached to the radially outer portion of the tubular member and the magnet assembly; and

[0068] The second drive unit suspension is separate from the first drive unit suspension in a direction extending parallel to the axis of motion, wherein the second drive unit suspension is attached to the radially outer portion of the tubular member and the magnet assembly, or to the radially inner portion of the voice coil frame and the magnet assembly.

[0069] Employing two separate drive unit suspensions along the axis of motion helps to significantly reduce rotation as described above in conjunction with Figure 2(c) and maintain good performance without substantially increasing the weight of the voice coil assembly. It should be noted that the tubular member allows for a larger spacing between the first and second drive unit suspensions. It should also be noted that the tubular member has an inherently rigid shape, thus allowing it to be formed from lightweight materials.

[0070] For typical applications, when measured in a direction parallel to the axis of motion, the distance between the positions of the two drive unit suspensions attached to the portions of the magnet assembly located radially outside the tubular member can be at least 3 mm, more preferably at least 5 mm, and even more preferably at least 6 mm. Those skilled in the art should recognize that the actual distance will vary depending on various factors, including the weight of the magnet assembly (greater weight requires a greater distance) and design constraints (e.g., the space in the hole to mount the speaker).

[0071] The magnet assembly may include a magnet assembly frame to which magnet units are attached, wherein the radially outer portion of the magnet assembly (to which at least one drive unit suspension is attached) is part of the magnet assembly frame.

[0072] The portion of the magnet assembly located radially outside the tubular member (on which at least one drive unit suspension is attached) may, for example, be the edge of the magnet assembly frame.

[0073] The radially outer portion of the magnet assembly located on the tubular member (to which at least one drive unit suspension is attached) may include a corresponding lug for attaching the drive unit suspension / each drive unit suspension to the radially outer portion of the magnet assembly located on the tubular member, thereby facilitating the attachment of one or more drive unit suspensions to the radially outer portion of the magnet assembly located on the tubular member.

[0074] The magnet assembly frame (included in the magnet assembly) may include holes configured to allow the insertion of clamps to center the tubular member during assembly.

[0075] The following describes some optional features of the driving unit described in this article:

[0076] A first plane perpendicular to the axis of motion, the first plane extending through the attachment portion;

[0077] A second plane perpendicular to the axis of motion extends through the air gap.

[0078] The features described with reference to the first and second planes are preferably described relative to the drive unit when the drive unit is at rest. As mentioned above, the drive unit can be considered to be at rest when no current is supplied to the voice coil.

[0079] The portion of the magnet assembly located radially outside the tubular member (to which at least one drive unit suspension is attached) may include:

[0080] The proximal end, wherein the proximal end of the portion of the magnet assembly located radially outward of the tubular member lies between the first plane and the second plane; and

[0081] The distal end, wherein the distal end of the portion of the magnet unit located radially outside the tubular member is located on the side of the second plane opposite to the proximal end (of the portion of the magnet assembly located radially outside the tubular member).

[0082] The magnet assembly may include a portion of the magnet assembly located radially inside the voice coil frame, wherein the portion of the magnet assembly located radially inside the voice coil frame includes:

[0083] The proximal end portion, wherein the proximal end portion of the magnet assembly located radially inward of the voice coil frame lies between the first plane and the second plane; and

[0084] The distal end, wherein the distal end of the portion of the magnet unit located radially inside the voice coil frame is located on the side of the second plane opposite to the proximal end of the portion of the magnet assembly located radially inside the voice coil frame.

[0085] The radially inner portion of the magnet assembly located within the voice coil frame may include a portion of the magnet unit. The proximal end of the radially inner portion of the magnet assembly located within the voice coil frame may, for example, include a portion of the magnet unit, such as the additional magnet 114a shown in FIG4(a)(i). The distal end of the radially inner portion of the magnet assembly located within the voice coil frame may, for example, include a portion of the magnet unit, such as the main magnet 112a shown in FIG4(a)(i).

[0086] Tubular components may include:

[0087] The proximal end, wherein the proximal end of the tubular member is located between the first plane and the second plane; and

[0088] The distal end, wherein the distal end of the tubular member is located on the side of the second plane opposite to the proximal end (of the tubular member).

[0089] Voice coil mounts may include:

[0090] The proximal end, wherein the proximal end of the voice coil carrier is located between the first plane and the second plane; and

[0091] The distal end, wherein the distal end of the voice coil is located on the side of the second plane opposite to the proximal end (of the voice coil).

[0092] It should be noted that if the tubular member has a distal end (as described above), this allows the tubular member to extend beyond the air gap on the outside of the magnet unit, and allows the first and second drive unit suspensions to be separated by a greater distance compared to an arrangement where the two drive unit suspensions are attached to the voice coil frame.

[0093] Preferably, the first drive unit suspension is attached to the distal end of the tubular member and the distal end of the portion of the magnet assembly located radially outward of the tubular member.

[0094] Preferably, the second drive unit suspension is attached to the proximal end of the tubular member and the proximal end of the portion of the magnet assembly located radially outward of the tubular member.

[0095] However, the second drive unit suspension may alternatively be attached to the proximal end of the voice coil frame and the proximal end of the portion of the magnet assembly located radially inward of the voice coil frame, while still allowing a wider gap between the first drive unit suspension and the second drive unit suspension, thereby still helping to reduce the rotation described above with reference to FIG2(c).

[0096] Preferably, the drive unit includes both of the following:

[0097] A first drive unit suspension is attached to the distal end of the tubular member and the distal end of the radially outer portion of the magnet assembly located on the tubular member; and

[0098] A second drive unit suspension is attached to the proximal end of the tubular member and the proximal end of the radially outer portion of the magnet assembly.

[0099] This arrangement allows for a particularly large space between the first drive unit suspension and the second drive unit suspension, which helps to reduce the rotation described above with reference to Figure 2(c).

[0100] In this arrangement, the drive unit may optionally include a third drive unit suspension attached to the proximal end of the voice coil frame and the proximal end of the portion of the magnet assembly located radially inward of the voice coil frame (e.g., as shown in FIG5(b)).

[0101] The tubular component preferably extends around the magnet unit.

[0102] The tubular member preferably overlaps with the magnet unit along at least a portion of the axis of motion.

[0103] The tubular member can be shaped to include an attachment to facilitate, for example, direct gluing (or some other attachment method) of the tubular member to the acoustic radiator.

[0104] Tubular components can be shaped to include attachments and voice coil frames.

[0105] The tubular member may include or be attached to a surface extending radially outward (relative to the axis of motion) from its distal end to provide a surface for attaching the tubular member to the first drive unit suspension. This surface may be flat. It may be provided by, for example, a ring made of plastic / cardboard.

[0106] The tubular member may include or be attached to a surface extending radially outward (relative to the axis of motion) from its proximal end to provide a surface for attaching the tubular member to the second drive unit suspension. This surface may be flat. It may be provided by, for example, a ring made of plastic / cardboard.

[0107] The wall of the tubular member can form an angle relative to the axis of motion, such that, for example, the distal end of the tubular member is farther from the axis of motion than the proximal end of the tubular member, thereby forming a truncated conical tubular member. In this case, the angle preferably does not exceed 15°.

[0108] The tubular member may have one or more extensions in a radially outward direction (relative to the axis of motion) to provide a corresponding attachment surface for the drive unit suspension / each drive unit suspension attached to the tubular member, thereby facilitating the attachment of the drive unit suspension / each drive unit suspension to the tubular member.

[0109] The width of the drive unit in the radial direction (perpendicular to the axis of motion) will typically depend on design requirements.

[0110] The drive unit may include one or more wires configured to provide an electrical path for supplying current carrying an audio signal (representing sound) to the voice coil.

[0111] An electrical path provided by one or more wires can extend from a connector formed on the magnet assembly (e.g., on the frame of the magnet assembly) to the voice coil.

[0112] One or more wires may include wires from the voice coil winding and / or leads connected to the voice coil winding.

[0113] One or more conductors may include conductors passing through or around the tubular member. Coupling elements (if present – ​​see below) may be configured to guide the conductors through or around the tubular member.

[0114] One or more wires may include wires that pass through or surround (preferably through) a frame included in a magnet assembly.

[0115] One or more conductors may include two conductors that converge at an electrical contact formed on the outer surface of the tubular member (e.g., at a solder pad or adhesive dot on the outer surface of the tubular member).

[0116] The magnet unit is preferably configured to provide a magnetic field in the air gap. The voice coil frame and / or tubular member can be cylindrical. However, the air gap, voice coil frame, and tubular member can have other shapes, such as elliptical and square.

[0117] Preferably, the voice coil holder is arranged around the axis of motion.

[0118] The voice coil frame preferably extends from the attachment in a direction that extends along the axis of motion into the air gap.

[0119] The tubular components and voice coil frame are each preferably made of lightweight materials (e.g., paper, cardboard, polyimide film (Kapton), aluminum, Kevlar, PE, ABS, etc.).

[0120] The tubular components and voice coil frame are preferably made of the same material, but they can also be made of different materials.

[0121] The tubular component and the voice coil frame can be integrally formed with each other (preferably with an attachment).

[0122] Preferably, the attachment is arranged around the axis of motion.

[0123] The attachment can be configured to provide attachment between the voice coil assembly and the acoustic radiator by including an adhesive surface configured to be glued to the acoustic radiator.

[0124] The attachment may be configured to provide attachment between the voice coil assembly and the acoustic radiator by including a bayonet feature (e.g., a protrusion) configured to engage with a corresponding bayonet feature (e.g., a slot) on the acoustic radiator to provide bayonet attachment between the attachment and the acoustic radiator.

[0125] The attachment may be a coupling element, which is attached separately to the voice coil frame and / or tubular member, for example, by adhesive.

[0126] The coupling element can be a ring-shaped element, such as a cardboard or plastic ring.

[0127] The coupling element is not a necessary element of the present invention, because the attachment portion can be integrally formed with the voice coil frame and / or tubular member. Alternatively, the voice coil and tubular member can be configured to be independently attached (e.g., by adhesive) to the sound radiator, in which case the attachment portion may include the adhesive and a portion of the sound radiator.

[0128] Drive unit suspension / Each drive unit suspension can take various forms.

[0129] Preferably, the drive unit suspension / each drive unit suspension includes one or more corrugations. In some examples, a drive unit suspension including one corrugation is preferred.

[0130] At least one drive unit suspension may include a speaker support ring. Each drive unit suspension may include a speaker support ring.

[0131] At least one drive unit suspension may include a coiled drive unit suspension. Each drive unit suspension may be a coiled drive unit suspension.

[0132] At least one drive unit suspension may include a sheet of material geometrically configured to allow deflection in a direction parallel to the axis of motion while suppressing movement in a direction perpendicular to the axis of motion. Each drive unit suspension may be a sheet of material geometrically configured to allow deflection in a direction parallel to the axis of motion while suppressing movement in a direction perpendicular to the axis of motion.

[0133] Compared to classic drive unit suspensions that typically require corrugations to deflect in the direction of the motion axis, a potential advantage of sheet drive unit suspensions could be reduced height (in the direction of the motion axis).

[0134] If there are two drive unit suspensions and each drive unit suspension includes one or more corrugations, then one or more corrugations in one drive unit suspension can be mirrored, for example, with respect to a plane perpendicular to the axis of motion with one or more corrugations in the other speaker support ring, thereby helping to eliminate, for example, asymmetry in stiffness.

[0135] The magnet unit may include a central main magnet and a U-shaped yoke.

[0136] In use, an audio signal-carrying current can be supplied to the voice coil. This current energizes the voice coil and generates a magnetic field within it. This magnetic field interacts with the magnetic field generated by the magnet unit in the air gap, causing the voice coil assembly to move relative to the magnet assembly. This relative movement is accommodated by at least one drive unit suspension.

[0137] The second aspect of the invention provides:

[0138] Speakers, including:

[0139] Mounting framework;

[0140] Acoustic radiator;

[0141] The drive unit includes:

[0142] A magnet assembly includes a magnet unit configured to provide a magnetic field in an air gap, wherein the air gap extends about the axis of motion of the exciter;

[0143] Voice coil assembly, including:

[0144] An attachment portion that provides attachment between the voice coil assembly and the acoustic radiator;

[0145] Voice coil;

[0146] A voice coil holder that extends from the attachment into the air gap, wherein the voice coil is mounted to the voice coil holder such that the voice coil is located in the air gap when the drive unit is at rest;

[0147] A tubular member located radially inside the voice coil frame relative to the axis of motion, and overlapping the voice coil frame along at least a portion of the axis of motion;

[0148] At least one drive unit suspension is attached to a portion of the tubular member and the magnet assembly located radially inside the tubular member, such that the acoustic radiator is suspended from the magnet assembly via the voice coil assembly through at least one drive unit suspension.

[0149] The magnet unit assembly is suspended from the mounting frame by at least one mounting frame suspension.

[0150] The speaker provided by the second aspect of the invention is similar to the speaker provided by the first aspect of the invention and provides substantially the same benefits as the speaker provided by the first aspect of the invention, but the components are arranged in a different order in the radial direction relative to the axis of motion.

[0151] The loudspeaker provided by the second aspect of the invention allows for the use of a ring magnet, which allows for the use of more magnetic material compared to examples of internal magnet types, and thus enables a more powerful drive unit (and loudspeaker), which may be desirable in some cases.

[0152] Therefore, the loudspeaker according to the second aspect of the invention can incorporate any one or more features described in connection with the loudspeaker according to the first aspect of the invention, but with a change in the order and orientation of certain elements in the drive unit in the radial direction (relative to the axis of motion) to achieve equivalent benefits. Similarly, the definitions described above with respect to the first aspect of the invention can be used in connection with the first aspect of the invention.

[0153] Some exemplary features of the loudspeaker according to the second aspect of the invention will now be described.

[0154] The axis of motion can be defined as such that when the drive unit is triggered by supplying a current carrying an audio signal to the voice coil, the voice coil assembly is configured to move relative to the magnet assembly along this axis.

[0155] When no current is supplied to the voice coil, the drive unit can be considered to be at rest.

[0156] It should be noted that in order to suspend the acoustic radiator from the magnet assembly via the voice coil assembly, the magnet assembly should be attached to the acoustic radiator only via the voice coil assembly, that is, there is no rigid attachment between the magnet assembly and the acoustic radiator.

[0157] Preferably, the drive unit includes:

[0158] The first drive unit suspension is attached to the radially inner portion of the tubular member and the magnet assembly; and

[0159] The second drive unit suspension is separate from the first drive unit suspension in a direction extending parallel to the axis of motion, wherein the second drive unit suspension is attached to the radially inner portion of the tubular member and the magnet assembly, or to the radially outer portion of the voice coil frame and the magnet assembly.

[0160] For typical applications, when measured in a direction parallel to the axis of motion, the distance between the positions of the two drive unit suspensions attached to the portions of the magnet assembly located radially inside the tubular member can be at least 3 mm, more preferably at least 5 mm, and even more preferably at least 6 mm. Those skilled in the art should recognize that the actual distance will vary depending on various factors, including the weight of the magnet assembly (greater weight requires greater distance) and design constraints (e.g., space in the hole for mounting the speaker).

[0161] The magnet assembly may include a magnet assembly frame to which magnet units are attached, wherein a portion of the magnet assembly located radially inside the tubular member (to which at least one drive unit suspension is attached) is part of the magnet assembly frame.

[0162] The portion of the magnet assembly located radially inside the tubular member (on which at least one drive unit suspension is attached) may, for example, be the central portion of the magnet assembly frame.

[0163] The radially inner portion of the magnet assembly located on the tubular member (to which at least one drive unit suspension is attached) may include a drive unit suspension for attaching to the radially inner portion of the magnet assembly located on the tubular member, or a corresponding lug for each drive unit suspension, thereby facilitating the attachment of one or more drive unit suspensions to the radially inner portion of the magnet assembly located on the tubular member.

[0164] The magnet assembly frame (included in the magnet assembly) may include holes configured to allow the insertion of clamps to center the tubular member during assembly.

[0165] The following describes some optional features of the driving unit described in this article:

[0166] A first plane perpendicular to the axis of motion, the first plane extending through the attachment portion;

[0167] A second plane perpendicular to the axis of motion extends through the air gap.

[0168] The features described with reference to the first and second planes are preferably described relative to the drive unit when the drive unit is at rest. As mentioned above, the drive unit can be considered to be at rest when no current is supplied to the voice coil.

[0169] The portion of the magnet assembly located radially inside the tubular member (on which at least one drive unit suspension is attached) may include:

[0170] The proximal end, wherein the proximal end of the portion of the magnet assembly located radially inward of the tubular member lies between the first plane and the second plane; and

[0171] The distal end, wherein the distal end of the portion of the magnet unit located radially inside the tubular member is located on the side of the second plane opposite to the proximal end (of the portion of the magnet assembly located radially inside the tubular member).

[0172] The magnet assembly may include a portion of the magnet assembly located radially outside the voice coil frame, wherein the portion of the magnet assembly located radially outside the voice coil frame includes:

[0173] The proximal end portion, wherein the proximal end portion of the magnet assembly located radially outward of the voice coil frame lies between the first plane and the second plane; and

[0174] The distal end, wherein the distal end of the portion of the magnet unit located radially outside the voice coil frame is located on the side of the second plane opposite to the proximal end (of the portion of the magnet assembly located radially outside the voice coil frame).

[0175] The radially outer portion of the magnet assembly located on the voice coil frame may include a portion of the magnet unit. The proximal end of the radially outer portion of the magnet assembly located on the voice coil frame may include, for example, a portion of the magnet unit, such as washer 213a as shown in FIG. 5(a). The distal end of the radially outer portion of the magnet assembly located on the voice coil frame may include, for example, a portion of the magnet unit, such as main magnet 212a as shown in FIG. 5(a).

[0176] Tubular components may include:

[0177] The proximal end, wherein the proximal end of the tubular member is located between the first plane and the second plane; and

[0178] The distal end, wherein the distal end of the tubular member is located on the side of the second plane opposite to the proximal end (of the tubular member).

[0179] Voice coil mounts may include:

[0180] The proximal end, wherein the proximal end of the voice coil carrier is located between the first plane and the second plane; and

[0181] The distal end, wherein the distal end of the voice coil is located on the side of the second plane opposite to the proximal end (of the voice coil).

[0182] It should be noted that if the tubular member has a distal end (as described above), this allows the tubular member to extend beyond the air gap on the inside of the magnet unit, and allows the first and second drive unit suspensions to be separated by a greater distance compared to an arrangement where the two drive unit suspensions are attached to the voice coil frame.

[0183] Preferably, the first drive unit suspension is attached to the distal end of the tubular member and the distal end of the portion of the magnet assembly located radially inside the tubular member.

[0184] Preferably, the second drive unit suspension is attached to the proximal end of the tubular member and the proximal end of the portion of the magnet assembly located radially inside the tubular member.

[0185] However, the second drive unit suspension may alternatively be attached to the proximal end of the voice coil frame and the proximal end of the radially outer portion of the magnet assembly (e.g., as shown in FIG5(c)), while still allowing a wider gap between the first drive unit suspension and the second drive unit suspension, thereby still helping to reduce the rotation described above with reference to FIG2(c).

[0186] Preferably, the drive unit includes both of the following:

[0187] A first drive unit suspension is attached to the distal end of the tubular member and the distal end of the portion of the magnet assembly located radially inward of the tubular member; and

[0188] A second drive unit suspension is attached to the proximal end of the tubular member and the proximal end of the portion of the magnet assembly located radially inward of the tubular member.

[0189] This arrangement allows for a particularly large space between the first drive unit suspension and the second drive unit suspension, which helps to reduce the rotation described above with reference to Figure 2(c).

[0190] In this arrangement, the drive unit may optionally include a third drive unit suspension attached to the proximal end of the voice coil frame and the proximal end of the radially outer portion of the magnet assembly (e.g., as shown in FIG5(b)).

[0191] The magnet unit preferably extends around the tubular member.

[0192] The tubular member preferably overlaps with the magnet unit along at least a portion of the axis of motion.

[0193] The tubular member can be shaped to include an attachment to facilitate, for example, direct gluing (or some other attachment method) of the tubular member to the acoustic radiator.

[0194] Tubular components can be shaped to include attachments and voice coil frames.

[0195] The tubular member may include or be attached to a surface extending radially inward (relative to the axis of motion) from its distal end to provide a surface for attaching the tubular member to the first drive unit suspension. This surface may be flat. It may be provided by, for example, a ring made of plastic / cardboard.

[0196] The tubular member may include or be attached to a surface extending radially inward (relative to the axis of motion) from its proximal end to provide a surface for attaching the tubular member to the second drive unit suspension. This surface may be flat. It may be provided by, for example, a ring made of plastic / cardboard.

[0197] The wall of the tubular member can form an angle relative to the axis of motion, such that, for example, the distal end of the tubular member is closer to the axis of motion than the proximal end of the tubular member, thereby forming a truncated conical tubular member. In this case, the angle preferably does not exceed 15°.

[0198] The tubular member may have one or more extensions in the radially inward direction (relative to the axis of motion) to provide a corresponding attachment surface for the drive unit suspension / each drive unit suspension attached to the tubular member, thereby facilitating the attachment of the drive unit suspension / each drive unit suspension to the tubular member.

[0199] The width of the drive unit in the radial direction (perpendicular to the axis of motion) will typically depend on design requirements.

[0200] The drive unit may include one or more wires configured to provide an electrical path for supplying current carrying an audio signal (representing sound) to the voice coil.

[0201] An electrical path provided by one or more wires can extend from a connector formed on the magnet assembly (e.g., on the frame of the magnet assembly) to the voice coil.

[0202] One or more wires may include wires from the voice coil winding and / or leads connected to the voice coil winding.

[0203] One or more conductors may include conductors passing through or around the tubular member. Coupling elements (if present – ​​see below) may be configured to guide the conductors through or around the tubular member.

[0204] One or more wires may include wires that pass through or surround (preferably through) a frame included in a magnet assembly.

[0205] One or more conductors may include two conductors that converge at an electrical contact formed on the inner surface of the tubular member (e.g., at a solder pad or adhesive dot on the inner surface of the tubular member).

[0206] The magnet unit is preferably configured to provide a magnetic field in the air gap. The voice coil frame and / or tubular member can be cylindrical. However, the air gap, voice coil frame, and tubular member can have other shapes, such as elliptical and square.

[0207] Preferably, the voice coil holder is arranged around the axis of motion.

[0208] The voice coil frame preferably extends from the attachment in a direction that extends along the axis of motion into the air gap.

[0209] The tubular components and voice coil frame are each preferably made of lightweight materials (e.g., paper, cardboard, polyimide film (Kapton), aluminum, Kevlar, PE, ABS, etc.).

[0210] The tubular components and voice coil frame are preferably made of the same material, but they can also be made of different materials.

[0211] The tubular component and the voice coil frame can be integrally formed with each other (preferably with an attachment).

[0212] Preferably, the attachment is arranged around the axis of motion.

[0213] The attachment can be configured to provide attachment between the voice coil assembly and the acoustic radiator by including an adhesive surface configured to be glued to the acoustic radiator.

[0214] The attachment can be configured to provide attachment between the voice coil assembly and the acoustic radiator by including a bayonet feature configured to engage with a corresponding bayonet feature on the acoustic radiator to provide bayonet attachment between the attachment and the acoustic radiator.

[0215] The attachment may be a coupling element, which is attached separately to the voice coil frame and / or tubular member, for example, by adhesive.

[0216] The coupling element can be a ring-shaped element, such as a cardboard or plastic ring.

[0217] The coupling element is not a necessary element of the present invention, because the attachment portion can be integrally formed with the voice coil frame and / or tubular member. Alternatively, the voice coil and tubular member can be configured to be independently attached (e.g., by adhesive) to the sound radiator, in which case the attachment portion may include the adhesive and a portion of the sound radiator.

[0218] Drive unit suspension / Each drive unit suspension can take various forms.

[0219] Preferably, the drive unit suspension / each drive unit suspension includes one or more corrugations. In some examples, a drive unit suspension including one corrugation (e.g., a coil drive unit suspension) is preferred.

[0220] At least one drive unit suspension may include a speaker support ring. Each drive unit suspension may include a speaker support ring.

[0221] At least one drive unit suspension may include a coiled drive unit suspension. Each drive unit suspension may be a coiled drive unit suspension.

[0222] At least one drive unit suspension may include a sheet of material geometrically configured to allow deflection in a direction parallel to the axis of motion while suppressing movement in a direction perpendicular to the axis of motion. Each drive unit suspension may be a sheet of material geometrically configured to allow deflection in a direction parallel to the axis of motion while suppressing movement in a direction perpendicular to the axis of motion.

[0223] Compared to classic drive unit suspensions that typically require corrugations to deflect in the direction of the motion axis, a potential advantage of sheet drive unit suspensions could be reduced height (in the direction of the motion axis).

[0224] If there are two drive unit suspensions and each drive unit suspension includes one or more corrugations, then one or more corrugations in one drive unit suspension can be mirrored, for example, with respect to a plane perpendicular to the axis of motion with one or more corrugations in the other speaker support ring, thereby helping to eliminate, for example, asymmetry in stiffness.

[0225] The magnet unit may include a ring-shaped main magnet and a T-shaped yoke.

[0226] In operation, an audio signal-carrying current is supplied to the voice coil, energizing it and generating a magnetic field. This magnetic field interacts with the magnetic field generated by the magnet unit in the air gap, causing the voice coil assembly to move relative to the magnet assembly. This relative movement is accommodated by at least one drive unit suspension.

[0227] Several features that can be applied to one or both of the loudspeakers according to the first aspect of the invention and the loudspeakers according to the second aspect of the invention will now be described:

[0228] Sound radiators can have various shapes (e.g., flat, curved, small, large, geometric, irregular).

[0229] The loudspeaker can be constructed as a dipole loudspeaker. The loudspeaker according to the first or second aspect of the invention is particularly well-suited for use as a dipole loudspeaker because its construction allows it to block a small area of ​​the radiating surface (generally referred to herein as the "second radiating surface") of the acoustic radiator to which it is attached.

[0230] The mounting frame can be part of a rigid support structure, or it can be constructed to be fixedly attached to a rigid support structure such as a car seat frame.

[0231] At least one mounting frame suspension can be tuned to have a resonant frequency lower than the frequency on which the speaker is constructed to operate, in order to, for example, limit forces on the support structure. The at least one mounting frame suspension can be tuned to have a resonant frequency of 20 Hz or lower, more preferably in the range of 10 Hz to 20 Hz. It should be noted that if there is more than one mounting frame suspension (e.g., two coil suspensions in the example of Figure 6(a)), the final stiffness of all mounting frame suspensions (along with the mass of the drive unit and the acoustic radiator) defines the resonant frequency.

[0232] One or more mounting frame suspensions can be tuned to have a resonant frequency lower than that of one or more drive unit suspensions tuned to have.

[0233] The mounting frame may include a rigid body extending around the axis of motion. This rigid body is preferably located radially outside the magnet unit relative to the axis of motion.

[0234] In some examples, the speaker may include a mounting frame suspension and a drive unit suspension, both of which are part of a single piece of material (in some examples, this may be an elastic material).

[0235] In some examples, the speaker may include:

[0236] The first mounting frame suspension and the first drive unit suspension, both of which are part of a first piece of material (in some examples, this may be an elastic material); and

[0237] The second mounting frame suspension and the second drive unit suspension are both part of a second piece of material (in some examples, this can be an elastic material).

[0238] The presence of two suspensions, which are part of the same piece of material, facilitates the manufacture of this speaker.

[0239] In some examples, at least one mounting frame suspension may include one or more roll-up suspensions, preferably at least two roll-up suspensions.

[0240] The material used for roll-up suspensions does not have to be elastic (for example, it could be textiles). This is because roll-up suspensions allow axial movement because there is excess material in the roll that “rolls out” during offset. However, due to this excess material, a single roll-up suspension typically does not provide a sufficient level of axial stability to prevent swaying, while two roll-up suspensions can.

[0241] In some examples, at least one mounting frame suspension may be formed of an elastic material (preferably a monolithic elastic material). The elastic material may be a monolithic elastic foam.

[0242] When using a monolithic elastic material, the suspension's flexibility relies on its elasticity. Therefore, if it's to sway, it must stretch the elastic material. The elastic material should be selected based on design requirements. Experiments show that monolithic elastic foam is suitable for a wide range of applications.

[0243] Preferably, the width of the acoustic radiator in at least one direction perpendicular to the axis of motion is greater than the width of the drive unit in the same direction. This means, for example, that the width of the acoustic radiator in at least one direction perpendicular to the axis of motion should be greater than the width of the drive unit (including the magnet assembly and voice coil assembly) in that direction. This at least one direction may include two orthogonal directions.

[0244] In other words, preferably, the acoustic radiator extends beyond each side of the drive unit in at least one direction perpendicular to the axis of motion.

[0245] By extending the diaphragm beyond the contour of the drive unit in at least one direction perpendicular to the axis of motion, the surface area of ​​the diaphragm can be maximized in a given headrest application. This is particularly meaningful if the loudspeaker is constructed to move the diaphragm at low frequencies and is configured to function as a dipole loudspeaker for enclosure purposes (e.g., as described in

[14] ), where 100cm 2 A larger radiating surface might be beneficial.

[0246] More generally, by extending the diaphragm beyond the contours of the driver unit, the loudspeaker is allowed to better approximate a perfect dipole.

[0247] In some examples, the width of the acoustic radiator in at least one direction perpendicular to the axis of motion can be at least 1.5 times (or even 2 times) the width of the drive unit in the same direction. In a headrest implementation (e.g., as described in

[14] ), this can allow the acoustic radiator to have a geometry that conforms to the headrest profile, which can help bring the diaphragm closer to the user's ear.

[0248] Preferably, the attachment is attached to the acoustic radiator at multiple locations on the acoustic radiator, wherein the centroid of the acoustic radiator is located between two of the multiple locations where the attachment is connected to the acoustic radiator.

[0249] In some examples, the acoustic radiator may have a laminated structure formed of at least two layers. The at least two layers may include a first layer of a first material having a first density (mass per unit volume) and a second layer of a second material having a second density, wherein the first density is lower than the second density.

[0250] In this way, the (denser and therefore heavier) second layer can provide additional stiffness to the first layer.

[0251] In some examples, the acoustic radiator may have a laminated structure formed of at least three layers. The at least three layers may include a first layer of a first material having a first density (mass per unit volume), wherein the first layer is sandwiched between a second layer of a second material having a second density and a third layer of a third material having a third density, wherein the first density is lower than the second and third densities.

[0252] In this way, the second and third layers (which are denser and therefore heavier) can provide additional stiffness to the first layer.

[0253] The third material can be the same as the second material, for example, as in the following Figure 6(e)(i) and 6(e)(ii) The example shown.

[0254] The second layer can partially cover only the surface of the first layer to which the second layer is attached, allowing the acoustic radiator to achieve the desired rigidity, for example, by using only a minimal amount of the (higher density and therefore heavier) second material. This can help optimize the weight of the acoustic radiator within the desired piston frequency range (e.g., up to 200 Hz before the first decomposition mode occurs).

[0255] For example, the second layer may cover 75% or less of the surface area of ​​the first layer to which the second layer is attached, preferably 50% or less of the surface area of ​​the first layer to which the second layer is attached.

[0256] The third layer (if present) can only partially cover the surface of the first layer to which the third layer is attached, allowing the acoustic radiator to have the required stiffness, for example, by using only a minimal amount of the (higher density and therefore heavier) third material. This can help optimize the weight of the acoustic radiator within the desired piston frequency range (e.g., up to 200 Hz before the first decomposition mode occurs).

[0257] For example, the third layer may cover 75% or less of the surface area of ​​the first layer to which the third layer is attached, preferably 50% or less of the surface area of ​​the first layer to which the third layer is attached.

[0258] Preferably, the first material comprises (preferably) polystyrene, and the second material comprises (preferably) balsa wood. Preferably, the third material (if present) comprises (preferably) balsa wood.

[0259] A sound radiator can have:

[0260] A first radiating surface, the first radiating surface being away from the driving unit and facing forward; and

[0261] The second radiating surface faces the drive unit in the rearward direction.

[0262] The voice coil assembly of the drive unit can be attached to the second radiating surface of the acoustic radiator (via the attachment).

[0263] The acoustic radiator can be curved, such that the first radiating surface is concave and its second radiating surface is convex. Furthermore, this allows the acoustic radiator to have a geometry that conforms to the contours of the headrest, which can help bring the diaphragm closer to the user's ear.

[0264] The acoustic radiator may have an extension on its periphery (e.g., outer edge) that extends in a rearward direction along the axis of motion. As described in more detail below, this can help maximize acoustic output and minimize wind noise in the gap between the acoustic radiator and the surrounding waveguide.

[0265] Drive unit suspension / Each drive unit suspension may extend in a linear direction in a plane perpendicular to the axis of motion, for example to improve motion linearity, to achieve silent operation and / or to avoid trapped air that would generate blowing noise.

[0266] The drive unit can be configured to move the diaphragm at low frequencies, such that the first radiating surface and the second radiating surface produce low-frequency sounds, wherein the sound produced by the first radiating surface is out of phase with the sound produced by the second radiating surface.

[0267] The driving unit is configured such that the bass frequencies of the moving diaphragm preferably include frequencies in the range of 60 Hz to 80 Hz (more preferably in the range of 50 Hz to 100 Hz, even more preferably in the range of 40 Hz to 100 Hz), and may include frequencies in the range of 40 Hz to 160 Hz. At these frequencies, the inventors have found that the loudspeaker is able to produce a particularly useful personal soundstage, the reasons for which are discussed in detail in

[14] .

[0268] Moving the diaphragm at frequencies below 40Hz may be beneficial for some applications, but not for others (e.g., in automobiles, where background noise below 40Hz is often too loud).

[0269] This speaker can be constructed as a subwoofer enclosure.

[0270] In some examples, the first radiating surface and the second radiating surface may each have a diameter of at least 100 cm. 2 The surface area, for example, is described in

[14] for the reasons.

[0271] Preferably, the frame of the magnet assembly (e.g., the "magnet assembly frame" as described above) and the mounting frame overlap at one or more locations observed in a plane perpendicular to the axis of motion. More preferably, the frame of the magnet assembly (e.g., the "magnet assembly frame" as described above) and the mounting frame overlap at two or more locations observed in a plane perpendicular to the axis of motion, for example, in a series of locations positioned along a path extending around the axis of motion (e.g., a circular path) (continuous or discontinuous). These overlaps can provide collision protection, as described below with reference to FIG. 6(f).

[0272] The speaker can be configured, for example, to be mounted within the headrest of the seat by including one or more mounting members configured to facilitate mounting the speaker within the headrest.

[0273] In a third aspect, the present invention may provide a seat assembly including a seat and a speaker according to the first or second aspect of the invention.

[0274] Preferably, the seat is configured to position the user sitting in the seat such that at least one of the user's ears is located at a listening position less than 40 cm (more preferably less than 30 cm, more preferably less than 25 cm, more preferably less than 20 cm, more preferably less than 15 cm) from the first radiating surface of the speaker (preferably, each of the user's ears is located at its respective listening position).

[0275] The speaker can be installed inside the headrest of the seat (“seat headrest”). Since a typical headrest is constructed at a short distance (e.g., less than 30 cm) from one or both ears of the user sitting in the seat, this is a particularly convenient way to position the user so that the user’s ears are located at a short distance (e.g., less than 30 cm) from the first radiating surface of the speaker.

[0276] A seat headrest typically has a front surface configured to face the head of a user sitting in the seat and a rear surface configured to face away from the head of the user sitting in the seat. A speaker is preferably mounted within the headrest, for example, with a first radiating surface of the speaker facing the front surface of the headrest, and for example, the main axis of the first radiating surface extending through the front surface of the headrest.

[0277] The loudspeaker can be configured as a dipole loudspeaker, for example, the loudspeaker can be installed in a seat headrest such that the seat headrest is configured to allow sound generated by a first radiating surface of the sound radiator to propagate through the front surface of the headrest and to allow sound generated by a second radiating surface of the sound radiator to propagate through the rear surface of the headrest.

[0278] The seat can have a rigid seat frame.

[0279] The speaker mounting frame can be part of a rigid seat frame or fixedly attached to a rigid seat frame.

[0280] The seat (e.g., the portion of the headrest on which a speaker is mounted) may include a waveguide that at least partially (preferably completely) surrounds the sound radiator and is configured to guide sound generated by a first radiating surface and / or a second radiating surface of the sound radiator.

[0281] Preferably, at one or more (preferably all) locations on the periphery (e.g., edge) of the acoustic radiator, the gap between the waveguide and the periphery of the acoustic radiator is less than 5 mm, more preferably less than 2 mm (e.g., in the range of 1 mm to 2 mm).

[0282] Seats can be vehicle seats used in vehicles such as cars (“car seats”) or airplanes (“airplane seats”).

[0283] Seats can be used on the exterior of vehicles. For example, a seat could be for computer gamers or for use in recording studios for monitoring or home entertainment.

[0284] In a fourth aspect, the invention can provide a means of transportation (e.g., a car or an airplane) having a plurality of seat assemblies as described in the third aspect of the invention.

[0285] The fifth aspect of the present invention provides:

[0286] A method for manufacturing a loudspeaker according to a first or second aspect of the invention.

[0287] The method may include: pre-assembling the voice coil assembly before suspending the magnet assembly from the voice coil assembly via at least one drive unit suspension.

[0288] The present invention includes combinations of the described aspects and preferred features, unless such combinations are obviously not permitted or should be explicitly avoided. Attached Figure Description

[0289] The implementation schemes and experiments based on the principles of the present invention will now be discussed and illustrated with reference to the accompanying drawings, wherein:

[0290] Figure 1(a) shows an exemplary conventional loudspeaker.

[0291] Figure 1(b) shows an exemplary inertial exciter.

[0292] Figure 2(a) shows a loudspeaker incorporating a wide-bandwidth inertial exciter that implements principles derived from existing technologies.

[0293] Figure 2(b) is a graph showing the force level of the loudspeaker shown in Figure 2(a) relative to the frequency.

[0294] Figure 2(c) illustrates a problem with the inertial exciter shown in Figure 2(a).

[0295] Figure 3 (a)(i) and Figure 3 (a)(ii) illustrates “Solution A” of the prior art teaching.

[0296] Figure 3 (b)(i) and Figure 3 (b)(ii) illustrates “Solution B” of the prior art teaching.

[0297] Figure 3 (c)(i) and Figure 3 (c)(ii) illustrates “Solution C” of the prior art teaching.

[0298] Figure 3 (d)(i) and Figure 3 (d)(ii) illustrates “Solution D” as taught by existing technology.

[0299] Figure 3 (e)(i) and Figure 3 (e)(ii) illustrates “Solution E” as taught by existing technology.

[0300] Figure 3 (f)(i) and Figure 3 (f)(ii) illustrates “Solution F” of the prior art teaching.

[0301] Figures 4(a)(i) to 4(a)(v) A first drive unit 101a, which is an example of a drive unit of the internal magnet type, and a speaker 180a incorporating the first drive unit 101a are shown.

[0302] Figures 4(b)(i) to 4(b)(iv) A second drive unit 101b, which is an example of an inertial exciter of the type of internal magnet, and a loudspeaker 180b incorporating the first drive unit 101b are shown.

[0303] Figure 4(c) shows a third drive unit 101c as an example of a drive unit of the internal magnet type.

[0304] Figure 4(d) shows a fourth drive unit 101d as an example of a drive unit of the internal magnet type.

[0305] Figure 4(e) shows a fifth drive unit 101e as an example of a drive unit of the internal magnet type.

[0306] Figure 4(f) shows the sixth drive unit 101f as an example of a drive unit of the internal magnet type.

[0307] Figure 4(g) shows the seventh drive unit 101g as an example of a drive unit of the internal magnet type.

[0308] Figure 4(h) shows an eighth drive unit 101h as an example of a drive unit of the internal magnet type.

[0309] Figure 4(i)(i) to Figure 4(i)(viii) The ninth drive unit 101i is shown as an example of a drive unit of the internal magnet type.

[0310] Figures 4(j)(i) to 4(j)(ii) The tenth drive unit 101j is shown as an example of a drive unit of the internal magnet type.

[0311] Figure 4(k) shows the eleventh drive unit 101k as an example of a drive unit of the internal magnet type.

[0312] Figure 4(l) shows the twelfth drive unit 101l as an example of a drive unit of the internal magnet type.

[0313] Figure 5(a) shows a first drive unit 201a as an example of a drive unit of the external magnet type.

[0314] Figure 5(b) shows a second drive unit 201b as an example of a drive unit of the external magnet type.

[0315] Figure 5(c) shows a third drive unit 201c as an example of a drive unit of the external magnet type.

[0316] Figure 5(d) shows a fourth drive unit 201d as an example of a drive unit of the external magnet type.

[0317] Figure 6(a) shows a first exemplary speaker.

[0318] Figure 6(b) shows a second exemplary speaker.

[0319] Figure 6(c) shows a third exemplary speaker.

[0320] Figures 6(d)(i) to 6(d)(iii) A fourth exemplary speaker is shown.

[0321] Figures 6(e)(i) to 6(e)(ii) A fifth exemplary speaker is shown.

[0322] Figure 6(f) shows a sixth exemplary speaker.

[0323] Figure 6(g) shows a seventh exemplary speaker.

[0324] Figure 6(h) shows the eighth exemplary speaker.

[0325] Figure 6(i) shows a seat headrest that combines a ninth exemplary speaker and a tenth exemplary speaker. Detailed Implementation

[0326] Various aspects and embodiments of the invention will now be discussed in conjunction with the accompanying drawings. Other aspects and embodiments will be apparent to those skilled in the art. All references herein are incorporated by way of citation.

[0327] For descriptive purposes, the exemplary drive unit is divided into two types, referred to as the "internal magnet" type according to the first aspect of the invention and the "external magnet" type according to the second aspect of the invention.

[0328] Drive Unit - Example of Internal Magnet Type

[0329] Figure 4(a)(i) shows a first drive unit 101a as an example of a drive unit of the internal magnet type.

[0330] Here, for completeness, please note that the drive unit 101a is referred to as the drive unit because it is intended for use in a loudspeaker, where a sound radiator is suspended from the magnet assembly of the drive unit.

[0331] If the drive unit 101a is intended for use in a loudspeaker (where the magnet assembly of the drive unit is suspended from the sound radiator), then the drive unit 101a can be alternatively referred to as an "inertial exciter". Therefore, the terms "drive unit" and "inertial exciter" can be used interchangeably with respect to the drive unit 101a until the drive unit 101a is incorporated into a loudspeaker, at which point the drive unit 101a should be referred to as an "inertial exciter" only if the loudspeaker has a magnet assembly of the drive unit suspended from the sound radiator.

[0332] The drive unit 101a in Figure 4(a)(i) includes a magnet assembly 102a and a voice coil assembly 104a.

[0333] The magnet assembly 102a includes a magnet unit 110a and a frame 120a to which the magnet unit 110a is attached.

[0334] In this example, magnet unit 110a includes a main magnet 112a, a washer 113a, an auxiliary magnet 114a, and a U-shaped yoke 115a. Magnet unit 110a is configured to provide a magnetic field in an air gap 116a. Air gap 116a extends about the axis of motion 106a of drive unit 101a.

[0335] The frame 120a includes a base 122a (in this example, from the base of the U-shaped yoke 115a) extending radially outward relative to the axis of motion 106a, and an edge 124a extending axially relative to the axis of motion 106a, i.e., extending at least partially along the axis of motion 106a. The edge 124a of the frame 120a is located at the periphery of the base 122a and is located radially outward of the magnet unit 110a.

[0336] The edge 124a of the frame 120a is located radially outside the tubular member 140a, and is therefore used as the "radially outside portion of the magnet assembly" mentioned in the above "Summary of the Invention" section of this document.

[0337] In this example, the main magnet 112a, washer 113a, auxiliary magnet 114a, U-shaped yoke 115a and air gap 116a are circular, but they can also be in other forms.

[0338] In this example, washer 114a and U-shaped yoke 116a can be made of steel, but they can also be made of other materials.

[0339] In this example, the voice coil assembly 104a includes a voice coil 130a, a voice coil holder 132a, a tubular member 140a, and an attachment portion 150a.

[0340] In this example, attachment 150a is a coupling element that is individually attached to the voice coil frame and tubular member, for example, by adhesive. Coupling element 150a is configured to provide attachment between the voice coil assembly 104a and the sound radiator by including an adhesive surface 151a configured to be glued to the sound radiator (not shown). Coupling element 150a can be, for example, a plastic or cardboard ring element.

[0341] The voice coil holder 132a extends axially from the coupling element 150a into the air gap 116a relative to the motion axis 106a. The voice coil 130a is mounted to the voice coil holder 132a such that when the drive unit 101a is at rest, the voice coil 130a is located in the air gap 116a.

[0342] The tubular member 140a is located radially outside the voice coil frame 132a relative to the axis of motion 106a. The tubular member 140a also overlaps with the voice coil frame 132a along a portion of the axis of motion (which corresponds to the full length of the voice coil frame 132a).

[0343] In this example, the voice coil holder 132a and the tubular member 140a are cylindrical, but they could also be other shapes.

[0344] Figure 4(a)(i) depicts two planes.

[0345] The first plane 108a is perpendicular to the axis of motion 106a and extends through the attachment portion, which, as described above, is the coupling element 150a.

[0346] The second plane 109a is perpendicular to the axis of motion 106a and extends through the air gap 116a.

[0347] Edge 124a of frame 120a includes:

[0348] The proximal end, wherein the proximal end of edge 124a is located between the first plane 108a and the second plane 109a; and

[0349] The distal end, wherein the distal end of edge 124a is located on the side of the second plane 109a opposite to the proximal end of edge 124a.

[0350] Similarly, the tubular member 140a includes:

[0351] The proximal end, wherein the proximal end of the tubular member 140a is located between the first plane 108a and the second plane 109a; and

[0352] The distal end, wherein the distal end of the tubular member 140a is located on the side of the second plane 109a opposite to the proximal end of the tubular member 140a.

[0353] The drive unit 101a includes:

[0354] A first drive unit suspension 160a is attached to the distal end of the tubular member 140a and the distal end of the edge 124a; and

[0355] The second drive unit suspension 165a is attached to the proximal end of the tubular member 140a and the proximal end of the edge 124a.

[0356] In this example, each drive unit suspension 160a, 165a is a speaker support ring comprising multiple corrugations. Such drive unit suspensions are well known in the art.

[0357] Therefore, when the voice coil assembly 104a is attached to the acoustic radiator via the attachment / coupling element 150a, the acoustic radiator is suspended from the magnet assembly 102a via the voice coil assembly 104a through the first drive unit suspension 160a and the second drive unit suspension 165a.

[0358] As can be seen from Figures 4(a)(i), the edge 124a of the frame 120a includes a first lug 125a and a second lug 126a, the first drive unit suspension 160a is attached to the first lug 125a, and the second drive unit suspension 165a is attached to the second lug 126a.

[0359] In this example, the first drive unit suspension 160a and the second drive unit suspension 165a are each shown as a corresponding speaker support ring with multiple corrugations.

[0360] The drive unit 101a includes wires 134a and 135a, which are configured to provide an electrical path for supplying current carrying an audio signal (representing sound) to the voice coil 130a.

[0361] Electrical pathways provided by wires 134a and 135a extend from connector 138a, which is formed on the outer surface of edge 124a of frame 120a, to voice coil 130a.

[0362] In this example, the conductor includes a portion of the voice coil winding 134a and a lead 135a. In this example, the voice coil winding 134a extends around the tubular member 140a under the guidance of the coupling element 150a.

[0363] The voice coil winding 134a and the lead wire 135a meet at the electrical contact formed at the pad or glue dot 136a on the outer surface of the tubular member 140a.

[0364] Figure 4(a)(ii) shows a loudspeaker 180a, including a drive unit 101a as shown in Figure 4(a)(i) and a sound radiator 190a suspended from a magnet assembly 102a, wherein the voice coil assembly 104a of the drive unit 101a is attached to the sound radiator 190a via an attachment / coupling element 150a, such that the sound radiator 190a is suspended from the magnet assembly 102a via a first drive unit suspension 160a and a second drive unit suspension 165a via the voice coil assembly.

[0365] Preferably, the magnet assembly 102a itself is suspended from the mounting frame via at least one mounting frame suspension (not shown here, but illustrated in the example described below entitled "Speaker with magnet assembly suspended from mounting frame").

[0366] In use, current carrying an audio signal is supplied to the voice coil 130a via connector 138a and wires 134a and 135a. This energizes the voice coil 130a and generates a magnetic field in the voice coil 130a. This magnetic field interacts with the magnetic field generated by the magnet unit 110a in the air gap 116a, causing the voice coil assembly 104a to move relative to the magnet assembly 102a. This relative movement is adjusted by the first drive unit suspension 160a and the second drive unit suspension 165a.

[0367] Because the acoustic radiator 190a is suspended from the magnet assembly 102a via the first drive unit suspension 160a and the second drive unit suspension 165a through the voice coil assembly 104a, the loudspeaker can be moved by MC and MM excitation.

[0368] Because the voice coil frame 132a and the tubular component 140a are tubular, they provide good rigidity even when made of lightweight materials such as paper, cardboard, Kapton, aluminum, and Kevlar. Therefore, the voice coil assembly 104a can have low weight and good rigidity, which is necessary for the good wide bandwidth performance derived from MC excitation.

[0369] Furthermore, because the tubular member 140a has a distal end that overlaps with the voice coil frame 132a to extend beyond the air gap 116a, that is, from the proximal end of the tubular member 140a to the opposite side of the second plane 109a, a large distance can be provided between the first drive unit suspension 160a and the second drive unit suspension 165a. This helps to suppress the rotation of the voice coil assembly 104a relative to the magnet assembly 102a when the loudspeaker is mounted vertically.

[0370] It is important to note that this is achieved while providing an acoustic radiator 190a for an interface (the glued surface of coupling element 150a) and also allowing MC excitation. As shown in Figures 4(a) and (iii), the low mass of the voice coil assembly (see above) contributes to achieving acoustic sensitivity and balance in the upper frequency band.

[0371] Figures 4(a) and (iv) illustrate the method steps involved in assembling the drive unit 101a, in which the voice coil carrier 132a is aligned in the air gap 116a using a conventional centering jig 195a before the components of the voice coil assembly 104a are bonded together. The coupling element 150a can be flush with the inner surface of the voice coil carrier 132a to facilitate the use of the centering jig 195a.

[0372] Figures 4(a)(v) illustrate alternative or additional method steps involved in assembling the drive unit 101a, wherein holes are incorporated into the frame 120a to allow centering jigs 196a to be inserted into these holes during assembly, for example to help align the voice coil holder 132a in the air gap 116a.

[0373] Preferably, the voice coil assembly (including the coupling element 150a of the voice coil 130a, the voice coil holder 132a, and the tubular member 140a) can be pre-assembled on a separate fixture (not shown) before being assembled into the magnet assembly 102a.

[0374] Various alternative examples of internal magnets will now be described. Similar features are given similar reference numerals where appropriate, and these similar features will not be described in further detail except where necessary.

[0375] Figure 4(b)(i) shows a second drive unit 101b as an example of a drive unit of the internal magnet type.

[0376] The coupling element 150b of the drive unit 101b is shown in FIG. 4(b)(ii) and includes bayonet features in the form of radial extensions 151b, which are configured to engage with corresponding bayonet features 191b on the acoustic radiator 190b shown in FIG. 4(b)(iii) to provide bayonet attachment between the coupling element 150b and the acoustic radiator 190b. The bayonet features 191b on the acoustic radiator preferably form slots for receiving the radial extensions 151b. The formed loudspeaker 180b is shown in FIG. 4(b)(iv).

[0377] The aforementioned bayonet features can facilitate the assembly and replacement of the drive unit 101b with the acoustic radiator 190b.

[0378] The aforementioned bayonet features can be combined with an adhesive or filler (e.g., grease) to avoid noise during operation. The adhesive or filler can have temperature-dependent properties, allowing the drive unit 101b to be replaced by heating.

[0379] Figure 4(c) shows a third drive unit 101c as an example of a drive unit of the internal magnet type.

[0380] In this example, the tubular member 140c includes a collar 141c that provides a flat surface for gluing a first drive unit suspension 160c, which in this example may be a fabric shock absorber, a metal or plastic coil spring, a rubber element, etc.

[0381] Figure 4(d) shows a fourth drive unit 101d as an example of a drive unit of the internal magnet type.

[0382] In this example, a ring 141d, for example made of cardboard or plastic, is attached to the distal end of the tubular member 140d to provide a flat surface 141d, thereby facilitating the gluing of the first drive unit suspension 160d.

[0383] Figure 4(e) shows a fifth drive unit 101e as an example of a drive unit of the internal magnet type.

[0384] In this example, the tubular member 140e is integrally formed with the attachment portion 150e by appropriately shaping the tubular member 140e to include the attachment portion 150e. This allows the tubular member 140e to be directly glued to the voice coil frame 132e and avoids the use of coupling elements as described in previous examples. In this example, the attachment portion 150e is a flat surface of the tubular member 140e configured to be glued to a sound radiator (not shown).

[0385] Tubular components 140e can be made of paper, cardboard, Kapton, aluminum, Kevlar, PE, ABS, etc.

[0386] Figure 4(f) shows a sixth drive unit 101f, which is an example of a drive unit of the internal magnet type.

[0387] The drive unit 101f is the same as the fifth drive unit 101e shown in FIG4(e), except that: a hole is formed in the attachment portion 150f to enhance the adhesive attachment with the acoustic radiator (not shown).

[0388] Figure 4(g) shows a seventh drive unit 101g, which is an example of a drive unit of the internal magnet type.

[0389] In this example, the coupling element 150g is attached only to the voice coil frame 132g, while the tubular member 140g is attached to the voice coil frame 132g.

[0390] Figure 4(h) shows an eighth drive unit 101h, which is an example of a drive unit of the internal magnet type.

[0391] In this example, the tubular member 140h forms an angle relative to the axis of motion, thereby forming a truncated conical tubular member 140h. In this case, the angle preferably does not exceed 15°.

[0392] The tubular component 140h formed in this way can facilitate the production of tubular components 140h from paper or plastic during deep drawing.

[0393] In this example, the tubular member 140h is appropriately shaped to include the attachment portion 150h, such that the tubular member 140h is also integrally shaped with the attachment portion 150h.

[0394] Figure 4(i)(i) shows a ninth drive unit 101i, which is an example of a drive unit of the internal magnet type.

[0395] This example is essentially the same as the first drive unit 101a shown in Figures 4(a)(i), except that: in this case, the first drive unit suspension 160i and the second drive unit suspension 165i consist of only a single corrugation, and these single corrugations (in plane 108i perpendicular to the axis of motion 106i) are mirror images of each other to help eliminate the stiffness asymmetry between the two drive unit suspensions 160i, 165i. In this case, the first drive unit suspension 160i and the second drive unit suspension 165i can be, for example, roll-type drive unit suspensions made of rubber, fabric, or foam.

[0396] Figures 4(i)(ii) illustrate the attachment between frame 120i and drive unit suspensions 160i and 165i. In this particular example, the edges of frame 120i are configured as two parts 124i(i) and 124i(ii).

[0397] Exemplary dimensions are plotted in Figures 4(i)(i) and 4(i)(ii). It can be noted that in this example, the distance between the positions where the two drive unit suspensions 160i and 165i are attached to the edge of the magnet assembly is 6.3 mm, which is relatively large for the overall size of the drive unit 101i.

[0398] Figures 4(i)(iii)-(viii) are 3D views showing the drive unit 101i from various angles.

[0399] Figure 4(j)(i) shows the tenth drive unit 101j as an example of a drive unit of the internal magnet type.

[0400] The drive unit 101j shown in Figure 4(j)(i) is the same as the drive unit 101a shown in Figure 4(a)(i), except that the drive unit includes an alternative form of the first drive unit suspension 160j and the second drive unit suspension 165j.

[0401] The alternative forms of drive unit suspensions for the first drive unit suspension 160j and the second drive unit suspension 165j are shown in more detail in Figures 4(j)(ii).

[0402] As can be seen most clearly from Figures 4(j)(ii), the alternative to the first drive unit suspension 160j and the second drive unit suspension 165j is a sheet of material whose geometry is configured to allow deflection in a direction parallel to the axis of motion 106j while suppressing movement in a direction perpendicular to the axis of motion 106j.

[0403] Suitable materials for alternative forms of the first drive unit suspension 160j and the second drive unit suspension 165j may be fiber-reinforced plastics, such as polymer matrices reinforced with glass fibers or carbon fibers, or metals (e.g., steel spring materials).

[0404] Figure 4(k) shows the eleventh drive unit 101k as an example of a drive unit of the internal magnet type.

[0405] The drive unit 101k shown in Figure 4(k) is the same as the drive unit 101a shown in Figure 4(a)(i), except that: in this example, the second drive unit suspension 165k is attached to the proximal end of the voice coil frame 132k and the proximal end of the portion of the magnet assembly located radially inside the voice coil frame (in this case, the additional magnet 114k).

[0406] It should be noted that, in this case, the drive unit 101k has:

[0407] A first drive unit suspension 160k is attached to the distal end of the tubular member 140k and the distal end of the edge 124k; and

[0408] The second drive unit suspension 165k is attached to the proximal end of the voice coil frame 132k and the proximal end of the portion of the magnet assembly located radially inside the voice coil frame 132k (in this case, the additional magnet 114k).

[0409] Therefore, this arrangement still allows for a relatively wide gap between the first drive unit suspension 160k and the second drive unit suspension 165k, which helps to suppress the rotation of the magnet assembly 102k relative to the voice coil assembly 104k.

[0410] In addition to providing a drive unit suspension, the second drive unit suspension 165k can also be used as a dust cover to prevent dust from entering the air gap 116k before the drive unit 101k is installed to the acoustic radiator.

[0411] In this example, the first drive unit suspension 165k is a coiled drive unit suspension consisting of only one corrugation.

[0412] Figure 4(l) shows the twelfth drive unit 101l, which is an example of a drive unit of the internal magnet type.

[0413] The drive unit 101l shown in Figure 4(l) is the same as the drive unit 101a shown in Figure 4(a)(i), except that: the third drive unit suspension 168l is attached to the proximal end of the voice coil frame 132l and the proximal end of the portion of the magnet assembly located radially inside the voice coil frame (in this case, the additional magnet 114l).

[0414] In addition to providing a drive unit suspension, the third drive unit suspension 168l can also be used as a dust cover to prevent dust from entering the air gap 116l before the acoustic radiator is installed to the drive unit 101l.

[0415] Drive Unit - Example of External Magnet Type

[0416] Figure 5(a) shows a first drive unit 201a as an example of a drive unit of the external magnet type.

[0417] The drive unit 201a shown in Figure 5(a) includes many of the same features as the drive unit 101a shown in Figure 4(a)(i). Similar features are given similar reference numerals where appropriate, and these similar features will not be described in further detail except where necessary.

[0418] The magnet assembly 202a includes a magnet unit 210a and a frame 220a to which the magnet unit 210a is attached.

[0419] In this example, magnet unit 210a includes a (ring-shaped) main magnet 212a, a (ring-shaped) washer 213a, and a T-shaped yoke 215a (as shown, which looks like an inverted "T"). Magnet unit 210a is configured to provide a magnetic field in air gap 216a. Air gap 216a extends about the axis of motion 206a of drive unit 201a.

[0420] An external magnet type example would be useful because, compared to an internal magnet type example, it allows for the use of more magnet material, thus enabling the creation of a more powerful exciter, which may be desirable in some cases.

[0421] In this example, frame 220a includes a base 222a that extends radially inward relative to axis of motion 206a (in this example, it extends from the base of T-shaped yoke 215a).

[0422] In this example, frame 220a also includes a central portion 224a that extends axially relative to the axis of motion 206a, i.e., at least partially along the axis of motion 206a. The central portion 224a of frame 220a is located at the center of base 222a and is located radially inside tubular member 240a.

[0423] In this example, the tubular member 240a is located radially inside the voice coil frame 232a relative to the axis of motion 206a, and overlaps with the voice coil frame 232a along at least a portion of the axis of motion 206a.

[0424] The drive unit 201a includes:

[0425] A first drive unit suspension 260a is attached to the distal end of the tubular member 240a and the distal end of the central portion 224a; and

[0426] The second drive unit suspension 265a is attached to the proximal end of the tubular member 240a and the proximal end of the central portion 224a.

[0427] As described above, the proximal ends of the tubular member 240a and the central portion 224a are located between the first plane 208a and the second plane 209a. The proximal ends of the tubular member 240a and the central portion 224a are located on the side of the second plane 209a opposite to the proximal ends.

[0428] As can be seen from Figure 5(a), the central portion 224a of the frame 220a includes a first lug 225a and a second lug 226a, the first drive unit suspension 260a is attached to the first lug 225a, and the second drive unit suspension 265a is attached to the second lug 226a.

[0429] In this example, the drive unit 201a includes a lead 234a configured to provide an electrical path for supplying current carrying an audio signal (representing sound) to the voice coil 130a.

[0430] In this example, the electrical path provided by the wire 234a extends from the connector 238a formed on the outward surface (outward in the sense of being away from the center portion 224a) of the base 222 of the frame 220a to the voice coil 230a.

[0431] In this example, lead 234a extends through frame 220a.

[0432] In this example, the coupling element 250a is similar to the coupling element shown in Figure 4(a)(i).

[0433] In use, a current carrying an audio signal is supplied to the voice coil 230a via connector 238a and lead 234a. This energizes the voice coil 230a and causes the current in the voice coil 230a to generate a magnetic field. This magnetic field interacts with the magnetic field generated by the magnet unit 210a in the air gap 216a, causing the voice coil assembly 204a to move relative to the magnet assembly 202a. This relative movement is accommodated by the first drive unit suspension 260a and the second drive unit suspension 265a.

[0434] Various alternative examples of internal magnets will now be described. Similar features are given similar reference numerals where appropriate, and these similar features will not be described in further detail except where necessary.

[0435] Figure 5(b) shows a second drive unit 201b as an example of a drive unit of the external magnet type.

[0436] This example is the same as the example shown in Figure 5(a), except that the third drive unit suspension 268b is attached to the radially outer portion of the voice coil frame 232b and the magnet assembly 202b (in this case, the washer 213b).

[0437] In addition to providing a drive unit suspension, the third drive unit suspension 268b can also be used as a dust cover to prevent dust from entering the air gap 216b when the drive unit 201b is in use.

[0438] Figure 5(c) shows a third drive unit 201c as an example of a drive unit of the external magnet type.

[0439] This example is the same as the example shown in Figure 5(a), except that in this example, the second drive unit suspension 265c is attached to the radially outer portion of the voice coil frame 232b and the magnet assembly 202b (in this case, the washer 213b).

[0440] It should be noted that, in this case, the drive unit 201c has:

[0441] A first drive unit suspension 260c is attached to the distal end of the tubular member 240c and the distal end of the central portion 224c; and

[0442] The second drive unit suspension 265c is attached to the proximal end of the tubular member 240c and the proximal end of the portion of the magnet assembly located radially outward of the tubular member 240c (in this case, washer 213b).

[0443] Therefore, this arrangement still allows for a relatively wide gap between the first and second drive unit suspensions 160k and the second drive unit suspension 165k, which helps to suppress the rotation of the magnet assembly 202c relative to the voice coil assembly 204c.

[0444] In addition to providing suspension, the second drive unit suspension 265c can also be used as a dust cover to prevent dust from entering the air gap 216c before the drive unit 201b is installed to the acoustic radiator.

[0445] Figure 5(d) shows a fourth drive unit 201d as an example of a drive unit of the external magnet type.

[0446] This example is the same as the example shown in Figure 5(b), except:

[0447] • By appropriately shaping the tubular member 240d to include the attachment portion 250d, the tubular member 240d and the attachment portion 250d are integrally formed.

[0448] • A hole is formed in the attachment portion 250d to enhance the adhesive attachment with the acoustic radiator (not shown).

[0449] Speaker with magnet assembly suspended from mounting frame

[0450] In all the following examples, the acoustic radiator is suspended from the magnet assembly via at least one drive unit suspension, and the magnet assembly is suspended from the mounting frame via at least one mounting frame suspension. Although this arrangement is explicitly shown only in the following examples, those skilled in the art will recognize that this arrangement can be equivalently used for all the drive units described above.

[0451] In the following exemplary loudspeakers, the drive unit includes many of the same features as the drive unit 101a shown in FIG. 4(a)(i). Similar features are given similar reference numerals where appropriate, and these features are not described in further detail except where necessary. In some examples, the acoustic radiator is omitted for clarity; however, it should be understood that in all cases, the loudspeaker will have an acoustic radiator attached to the voice coil assembly, wherein the attachment provides the connection between the voice coil assembly and the acoustic radiator.

[0452] In all the examples below, the speaker incorporates an external magnet type drive unit, but those skilled in the art should readily recognize that an internal magnet type drive unit can also be used.

[0453] In all the following examples, the loudspeaker is preferably configured to move the diaphragm at low frequencies and to function as a dipole loudspeaker, for example as described in

[14] .

[0454] Figure 6(a) shows a first exemplary loudspeaker 300a, wherein an acoustic radiator 390a is attached to a voice coil assembly 304a, wherein an attachment portion 350a provides attachment between the voice coil assembly 304a and the acoustic radiator 390a.

[0455] As shown in Figure 6(a), the loudspeaker 300a also includes a mounting frame 380a, from which the magnet unit assembly 302a is suspended by at least one mounting frame suspension 370a, 375a. In this example, the magnet unit assembly is suspended from the mounting frame by two mounting frame suspensions 370a, 375a, both of which are coil suspensions in this example, wherein individual corrugations (in a plane perpendicular to the axis of motion) are mirror images of each other to help eliminate stiffness asymmetry between the two mounting frame suspensions 370a, 375a.

[0456] In this example, the mounting frame 380a is configured to be securely (i.e. rigidly) attached to a rigid support structure, such as an automotive seat frame, by including one or more mounting elements. In this example, the mounting elements are holes 392a through which bolts can pass to fasten the mounting frame 380a to the rigid support structure.

[0457] To facilitate the use of bolts, the acoustic radiator 390a may include one or more contact holes 392a to provide contact to one or more mounting elements. When the contact is no longer needed, one or more contact holes 392a can be sealed with tape 393a to reduce / avoid acoustic performance loss due to the presence of the one or more contact holes. Of course, other acoustic radiator structures are also possible.

[0458] As shown in Figure 6(a), the width of the acoustic radiator 390a in the direction d perpendicular to the motion axis 306a is greater than the width of the drive unit 301a in the same direction. In other words, the acoustic radiator 390a extends beyond each side of the drive unit 301a in at least one direction (d) perpendicular to the motion axis.

[0459] The acoustic radiator 390a has: a first radiating surface 394a facing forward in a direction F away from the drive unit 301a; and a second radiating surface 394a' facing backward in a direction B toward the drive unit; wherein the voice coil assembly 304a of the drive unit 301a is attached to the second radiating surface 394a' of the acoustic radiator (via an attachment portion 350a).

[0460] Figure 6(b) shows a second exemplary loudspeaker 300b, in which the sound radiator is omitted for clarity.

[0461] In this example, speaker 300b includes:

[0462] A first mounting frame suspension 360b and a first drive unit suspension 370b, both of which are part of a first piece of material (in some examples, this could be an elastic material); and

[0463] The second mounting frame suspension 365b and the second drive unit suspension 375b are both part of a second piece of material (in some examples, this may be an elastic material).

[0464] In this configuration, the magnet unit 310b includes two pole components having a groove 317b at the voice coil location. This groove 317b may, for example, be filled with copper.

[0465] The first drive unit suspension 360b and / or the second drive unit suspension 365b may include one or more holes / interruptions to help silence their operation. In this particular example, the first drive unit suspension 360b is perforated to achieve this effect.

[0466] Figure 6(c) shows a third exemplary speaker 300c.

[0467] In this example, the acoustic radiator 390c is curved, such that the first radiating surface 394c is concave and the second radiating surface 394c' is convex.

[0468] The first drive unit suspension and / or the second drive unit suspension may include one or more interruptions to facilitate the attachment of the lead 334c. In this particular example, the second drive unit suspension 365c includes an interruption through which the lead 334c passes.

[0469] Furthermore, the width of the acoustic radiator 390c in the direction d perpendicular to the axis of motion is greater than the width of the drive unit 301c in the same direction.

[0470] Figures 6(d)(i) to 6(d)(iii) A fourth exemplary speaker 300d is shown.

[0471] In this example, the acoustic radiator 390d is curved, such that the first radiating surface 394d is concave and its second radiating surface 394d' is convex.

[0472] Furthermore, the width of the acoustic radiator 390d in the direction d perpendicular to the axis of motion is greater than the width of the drive unit 301d in the same direction.

[0473] The attachment portion 350d is attached to the acoustic radiator 390d at multiple locations, wherein the center of mass of the acoustic radiator 390d is located between two of the multiple locations where the attachment portion 350d is attached to the acoustic radiator, preferably such that the acoustic radiator is driven (substantially) at its center of mass. In this example, the center of mass is located on the axis of motion 306d, and therefore between the two locations where the attachment portion 350d is attached to the acoustic radiator 390d in the cross-sectional plane shown in FIG. 6(d)(iii) (these two locations correspond to the two points marked by reference numeral 350d in FIG. 6(d)(iii).

[0474] In this example, drive unit suspensions 360d and 365d each extend in a linear direction in a plane perpendicular to the axis of motion, for example, to improve motion linearity, achieve silent operation, and / or avoid trapped air that would generate blowing noise. Interruptions in the drive unit suspensions 360d and 365d are provided by the gap between the linear suspensions.

[0475] Figures 6(e)(i) and 6(e)(ii) show a fifth exemplary loudspeaker 300e, wherein Figure 6(e)(i) is a view of the front (forward) surface of the loudspeaker 300e, and Figure 6(e)(ii) is a view of the rear (rear) surface of the loudspeaker 300e.

[0476] In this example, the speaker 300e shares many features with the exemplary speaker shown in FIG. 6(b), but in this case, the sound radiator 390e has a laminated structure formed of three layers: a polystyrene layer 395e sandwiched between two balsa wood layers 395e', 395", wherein the first balsa wood layer 395e' is attached to the first (front) side of the polystyrene layer 395e, and the second balsa wood layer 395e' is attached to the second side of the polystyrene layer 395e.

[0477] The first balsa wood layer 395e' covers 75% or less of the surface area of ​​the polystyrene layer 395e to which the first balsa wood layer 395e' is attached, and the portion of the surface of the first balsa wood layer 395e' and the polystyrene layer 395e exposed behind the first balsa wood layer 395e' provides the first radiating surface 394e of the acoustic radiator 390e.

[0478] The second balsa wood layer 395e” covers 75% or less of the surface area of ​​the polystyrene layer 395e to which the second balsa wood layer 395e” is attached, and the portion of the surface of the second balsa wood layer 395e” and the polystyrene layer 395e exposed behind the second balsa wood layer 395e” provides the second radiating surface 394e' of the acoustic radiator 390e.

[0479] The first balsa wood layer 395e' and the second balsa wood layer 395e" help to harden the sound radiator 390e.

[0480] The polystyrene in the polystyrene layer 395e is preferably expanded, but can also be extruded. Exemplary parameters of the polystyrene layer 395e may be:

[0481] • Density: as low as possible, for example, 15 kg / m³ 3 Up to 60kg / m 3

[0482] • The elastic modulus (related to density) can range from 1.4 MPa to 4.0 MPa.

[0483] • The thickness can be up to 10mm, preferably 3mm to 5mm.

[0484] The balsa wood in balsa layers 395e' and 395e" can be balsa veneer or balsa leaf. If balsa veneer is used, the grain direction of the balsa wood preferably extends in the direction of its longest length. Exemplary parameters for each balsa layer 395e' and 395e" can be:

[0485] Density: 100kg / m³ 3 Up to 150kg / m 3

[0486] • The flexural modulus along the texture can range from 3.5 GPa to 5 GPa (note that the flexural modulus increases with frequency).

[0487] The thickness can be from 0.5mm to 1.5mm.

[0488] It should be noted that each balsa wood layer 395e', 395e” only covers a portion of the surface formed by the polystyrene layer 395e, so that the required stiffness can be achieved, for example, with only a minimal amount of balsa wood.

[0489] Figure 6(f) shows the sixth exemplary speaker 300f.

[0490] In this example, the acoustic radiator 390f has a laminated structure formed of at least two layers, wherein the at least two layers include a first layer of a first material having a first density and a second layer of a second material having a second density, wherein the first density is lower than the second density. In some examples, an additional third layer of second material may be present, wherein the first layer is sandwiched between the second layer of second material and the third layer of second material having the second density. For example, the first material and the second material may be:

[0491] Balsamic foam

[0492] Paper-foam

[0493] Paper-honeycomb structure

[0494] Carbon fiber-foam

[0495] · Fiberglass-paper

[0496] Laminated structures consisting of two layers of the same material are also possible, such as balsa wood-balsa wood.

[0497] In this example, the attachment portion 350f of the drive unit 301f includes alignment features configured to engage with corresponding alignment features 391f (illustrated here as a base) on the acoustic radiator 390f, facilitating alignment and easy attachment of the attachment portion 350f and the acoustic radiator 390f. This attachment can be mechanical (e.g., screw, bayonet, or thermal welding) or chemical (adhesive).

[0498] This example illustrates two alternative forms of collision protection (circled in dashes) at two locations where the frame of the magnet assembly 302f overlaps with the mounting frame 380f when viewed in a plane perpendicular to the axis of motion 306f (e.g., plane 308f). These collision protection features help prevent the magnet assembly 302f from protruding from the headrest during a collision in a vehicle in which the speaker 300f is mounted within the headrest.

[0499] Of course, there may be only one of the collision protection features shown in Figure 6(f), instead of both. Similarly, any one or both of these collision protection features may exist continuously (or discontinuously) along a path extending around the axis of motion.

[0500] Figure 6(g) shows the seventh exemplary speaker 300g.

[0501] In this example, the acoustic radiator 390g may have an extension on its periphery (outer edge) that extends along the axis of motion in the rearward direction B.

[0502] To demonstrate the different schemes, Figure 6(g) shows two possible extensions.

[0503] In the first form, the extension 397g is a component of the acoustic radiator, which is folded to extend in a rearward direction along the axis of motion.

[0504] In the second form, the extension is provided by a foam strip 397g' which is attached (e.g., by adhesive) to the remainder of the acoustic radiator 390g around the periphery of the acoustic radiator 390g.

[0505] The seat (e.g., the portion of the headrest on which a speaker is mounted) may include a waveguide 378g that at least partially (preferably completely) surrounds the acoustic radiator 390g and is configured to guide sound generated by a first radiating surface and / or a second radiating surface of the acoustic radiator 390g.

[0506] Preferably, at one or more (preferably all) locations around the periphery of the acoustic radiator 390g, the gap between the waveguide and the periphery of the acoustic radiator is less than 5 mm, more preferably less than 2 mm (e.g., in the range of 1 mm to 2 mm).

[0507] Figure 6(h) shows the eighth exemplary speaker 300h.

[0508] In this example, there is only one mounting frame suspension 370h, which is formed of elastic foam, preferably a single piece of elastic foam, which may have the properties described in

[15] , but other forms of elastic foam are of course also possible.

[0509] Figure 6(i) shows a seat headrest 1000i, which combines a ninth speaker 300i and a tenth speaker 300i', and also combines two mid-high frequency speakers 1010i and 1010i'.

[0510] The two mid-high frequency loudspeakers 1010i and 1010i' can be cardioid, for example as described in

[16] , but other forms of mid-high frequency loudspeakers are of course also possible.

[0511] Figure 6(i) also shows:

[0512] · Electronic unit 1015i

[0513] • The headrest base 1030i (the headrest base 1030i is part of the rigid seat frame) is attached to the mounting frame 380i of the speaker 300i.

[0514] • Acoustic-permeable decorative materials 1020i, such as perforated leather, textiles, etc. (Note that for aesthetic reasons, each part can remain opaque)

[0515] • The open-cell elastic foam 1025i is preferably acoustically transparent in front of the sound radiators 300i, 300i' (this can be combined with opaque foam areas to improve support comfort).

[0516] The features disclosed in the foregoing description, the following claims, or the accompanying drawings (expressed in their specific form or as means for performing the disclosed functions or as methods or processes for obtaining the disclosed results) may, where appropriate, be used alone or in any combination of these features to implement the invention in different forms.

[0517] Although the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when this disclosure is given. Therefore, the exemplary embodiments described above are to be considered illustrative rather than restrictive. Various changes may be made to the described embodiments without departing from the spirit and scope of the invention.

[0518] To avoid any doubt, any theoretical explanations provided herein are intended to enhance the reader's understanding. The inventor does not wish to be bound by any of these theoretical explanations.

[0519] Any chapter headings used in this document are for organizational purposes only and should not be construed as limiting the subject matter described.

[0520] Throughout this specification (including the following claims), unless the context otherwise requires, the words “comprising,” “including,” and variations thereof such as “comprising,” “including,” and “including” should be understood to implicitly include the stated whole or step or combination of whole or steps, but do not exclude any other whole or step or combination of whole or steps.

[0521] It must be noted that, unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” used in this specification and the appended claims all include plural referents. A range herein may be expressed as from “about” one particular value and / or to “about” another particular value. When expressing such a range, another embodiment includes from one particular value and / or to another particular value. Similarly, when a value is expressed as an approximation using the antecedent “about,” it should be understood that the particular value forms another embodiment. The term “about” in relation to numerical values ​​is optional and means, for example, + / - 10%.

[0522] References

[0523] Numerous publications have been cited above to provide a more comprehensive description and disclosure of the invention and the current state of the art to which it pertains. The full citations of these references are provided below. The entire contents of each of these references are incorporated herein by reference.

[0524] ·[1]US6618487B1

[0525] ·[2]US4506117A

[0526] ·[3]US8247930B2

[0527] ·[4]US7372968B2

[0528] ·[5]US4550428A

[0529] ·[6]US6965679B1

[0530] ·[7]US2005 / 180587A1

[0531] ·[8]US4675907A

[0532] ·[9]US4354067A

[0533] ·

[10] US4750208A

[0534] ·

[11] DE102004009902A1

[0535] ·

[12] US9621994B1

[0536] ·

[13] US5734132

[0537] ·

[14] WO2019 / 121266

[0538]

[15] GB2008724.3

[0539] ·

[16] GB2004076.2

Claims

1. A loudspeaker, including: Mounting framework; Acoustic radiator; The drive unit includes: Magnet assembly, including: A magnet unit configured to provide a magnetic field in an air gap, wherein the air gap extends about the axis of motion of the drive unit; A magnet assembly frame, wherein the magnet unit is attached to the magnet assembly frame; Voice coil assembly, including: The attachment portion provides an attachment between the voice coil assembly and the acoustic radiator; Voice coil; A voice coil holder extending from the attachment portion into the air gap, wherein the voice coil is mounted to the voice coil holder such that the voice coil is located in the air gap when the drive unit is at rest; A tubular member, the tubular member being located radially outside the voice coil frame relative to the axis of motion, and overlapping the voice coil frame along at least a portion of the axis of motion; The first drive unit suspension is attached to the radially outer portion of the tubular member and the magnet assembly frame; The second drive unit suspension is separate from the first drive unit suspension in a direction extending parallel to the axis of motion, wherein the second drive unit suspension is attached to the radially outer portion of the tubular member and the magnet assembly frame, or to the radially inner portion of the voice coil frame and the magnet assembly. The acoustic radiator is suspended from the magnet assembly via the voice coil assembly through the first drive unit suspension and the second drive unit suspension; The magnet assembly is suspended from the mounting frame by at least one mounting frame suspension; and The width of the acoustic radiator in at least one direction perpendicular to the axis of motion is greater than the width of the drive unit in the same direction.

2. The loudspeaker according to claim 1, wherein: The first drive unit suspension is attached to the distal end of the tubular member and the distal end of the portion of the magnet assembly located radially outward of the tubular member.

3. The loudspeaker according to claim 2, wherein: The second drive unit suspension is attached to the proximal end of the tubular member and the proximal end of the portion of the magnet assembly located radially outward of the tubular member.

4. Loudspeakers, including: Mounting framework; Acoustic radiator; The drive unit includes: Magnet assembly, including: A magnet unit configured to provide a magnetic field in an air gap, wherein the air gap extends about the axis of motion of the drive unit; A magnet assembly frame, wherein the magnet unit is attached to the magnet assembly frame; Voice coil assembly, including: The attachment portion provides an attachment between the voice coil assembly and the acoustic radiator; Voice coil; A voice coil holder extending from the attachment portion into the air gap, wherein the voice coil is mounted to the voice coil holder such that the voice coil is located in the air gap when the drive unit is at rest; A tubular member, the tubular member being located radially inside the voice coil frame relative to the axis of motion, and overlapping the voice coil frame along at least a portion of the axis of motion; The first drive unit suspension is attached to the portion of the tubular member and the magnet assembly frame located radially inside the tubular member; The second drive unit suspension is separate from the first drive unit suspension in a direction extending parallel to the axis of motion, wherein the second drive unit suspension is attached to the radially inner portion of the tubular member and the magnet assembly frame, or to the radially outer portion of the voice coil frame and the magnet unit. The acoustic radiator is suspended from the magnet assembly via the voice coil assembly through the first drive unit suspension and the second drive unit suspension; The magnet assembly is suspended from the mounting frame by at least one mounting frame suspension; and The width of the acoustic radiator in at least one direction perpendicular to the axis of motion is greater than the width of the drive unit in the same direction.

5. The loudspeaker according to claim 4, wherein: The first drive unit suspension is attached to the distal end of the tubular member and the distal end of the portion of the magnet assembly located radially inward of the tubular member.

6. The loudspeaker according to claim 5, wherein: The second drive unit suspension is attached to the proximal end of the tubular member and the proximal end of the portion of the magnet assembly located radially inward of the tubular member.

7. The loudspeaker according to any one of claims 1 to 6, wherein the tubular member is shaped to include the attachment portion.

8. The loudspeaker of claim 7, wherein the tubular member is shaped to further include the voice coil frame.

9. The loudspeaker according to any one of claims 1 to 6, wherein the tubular member has one or more extensions in a radial direction relative to the axis of motion to provide a corresponding attachment surface for the drive unit suspension / each drive unit suspension to be attached to the tubular member, thereby facilitating the attachment of the drive unit suspension / each drive unit suspension to the tubular member.

10. The loudspeaker according to any one of claims 1 to 6, wherein the attachment is a coupling element that is individually attached to the voice coil frame and / or the tubular member.

11. The loudspeaker according to any one of claims 1 to 6, wherein the attachment is configured to provide attachment between the voice coil assembly and the acoustic radiator by including a bayonet feature, the bayonet feature being configured to engage with a corresponding bayonet feature on the acoustic radiator to provide bayonet attachment between the attachment and the acoustic radiator.

12. The loudspeaker according to any one of claims 1 to 6, wherein the driving unit comprises one or more wires configured to provide an electrical path for supplying current carrying an audio signal to the voice coil, wherein: The electrical path provided by the one or more wires extends from the connector formed on the magnet assembly to the voice coil; and / or The one or more conductors include conductors that pass through or surround the tubular member; and / or The coupling element is configured to guide one or more conductors through or around the tubular member; and / or The one or more conductors may include conductors passing through a frame included in the magnet assembly.

13. The loudspeaker according to any one of claims 1 to 6, wherein the at least one mounting frame suspension is tuned to have a resonant frequency in the range of 10 Hz to 20 Hz.

14. The loudspeaker according to any one of claims 1 to 6, wherein the loudspeaker comprises a mounting frame suspension and a drive unit suspension, both of which are part of a single piece of material.

15. The loudspeaker according to any one of claims 1 to 6, wherein the loudspeaker comprises: The first mounting frame suspension and the first drive unit suspension are both part of the first piece of material; as well as The second mounting frame suspension and the second drive unit suspension are both part of the second piece of material.

16. The loudspeaker according to any one of claims 1 to 6, wherein the at least one mounting frame suspension is formed from a single piece of elastic material.

17. The loudspeaker according to any one of claims 1 to 6, wherein the acoustic radiator has a laminated structure formed of at least two layers, wherein the at least two layers comprise a first layer of a first material having a first density and a second layer of a second material having a second density, wherein the first density is lower than the second density.

18. The loudspeaker of claim 17, wherein the acoustic radiator has a stacked structure formed of at least three layers, wherein the at least three layers include a first layer of a first material having a first density, wherein the first layer is sandwiched between a second layer of a second material having a second density and a third layer of a third material having a third density, wherein the first density is lower than the second density and the third density.

19. The loudspeaker of claim 17, wherein the second layer covers 75% or less of the surface area of ​​the surface of the first layer to which the second layer is attached.

20. The loudspeaker of claim 18, wherein the third layer covers 75% or less of the surface area of ​​the first layer to which the third layer is attached.

21. The loudspeaker of claim 17, wherein the first material is polystyrene and the second material is balsa wood, wherein, If a third material is present, then the third material is balsa wood.

22. The loudspeaker according to any one of claims 1 to 6, wherein: The acoustic radiator has: A first radiating surface, the first radiating surface being away from the driving unit and facing forward; as well as The second radiating surface faces the rearward direction of the driving unit. The voice coil assembly of the driving unit is attached to the second radiating surface of the acoustic radiator; The acoustic radiator is curved, such that the first radiating surface is concave and its second radiating surface is convex.

23. The loudspeaker according to any one of claims 1 to 6, wherein the loudspeaker is a subwoofer enclosure configured as a dipole loudspeaker.

24. The loudspeaker according to any one of claims 1 to 6, wherein the magnet assembly frame and the mounting frame overlap at one or more locations observed in a plane perpendicular to the axis of motion.

25. A seat assembly, comprising: Seats; as well as The loudspeaker according to any one of claims 1 to 24.

26. The seat assembly of claim 25, wherein the seat is configured to position a user sitting in the seat such that each of the user's ears is located at a corresponding listening position less than 25 cm from the first radiating surface of the speaker.

27. The seat assembly of claim 25, wherein the seat is configured to position a user sitting in the seat such that each of the user's ears is located at a corresponding listening position less than 20 cm from the first radiating surface of the speaker.

28. The seat assembly of claim 25, wherein the speaker is mounted in the headrest of the seat.

29. The seat assembly according to any one of claims 25 to 28, wherein the seat has a rigid seat frame, and the mounting frame of the speaker is part of or fixedly attached to the rigid seat frame.

30. The seat assembly according to any one of claims 25 to 28, wherein the seat includes a waveguide that at least partially surrounds the acoustic radiator and is configured to guide sound generated by a first radiating surface and / or a second radiating surface of the acoustic radiator.

31. The seat assembly of claim 30, wherein the waveguide is disposed in the headrest of the seat.

32. The seat assembly of claim 30, wherein at one or more locations around the periphery of the acoustic radiator, the gap between the waveguide and the periphery of the acoustic radiator is less than 5 mm.

33. A method of manufacturing a loudspeaker according to any one of claims 1 to 24, wherein the method comprises: The voice coil assembly is pre-assembled before the magnet assembly is suspended from the voice coil assembly by the first drive unit suspension and the second drive unit suspension.

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