Dipole loudspeaker assembly

Abstract

A dipole loudspeaker assembly for producing low frequency sound includes a dipole loudspeaker including a diaphragm having two radiating surfaces opposite each other that each produce low frequency sound, the sound produced by the first radiating surface being out of phase with the sound produced by the second radiating surface. The dipole loudspeaker includes a driver unit frame that allows the sound produced by the first radiating surface and the sound produced by the second radiating surface to propagate out of the dipole loudspeaker from opposite sides, respectively, the diaphragm being suspended from the driver unit frame via a driver unit suspension. The dipole loudspeaker assembly includes a mounting frame from which the driver unit frame is suspended via a mounting frame suspension. The mounting frame suspension at least partially overlaps, when projected onto a plane perpendicular to the axis of motion, one or more elements selected from the group consisting of the diaphragm and the driver unit suspension when projected onto the same plane. At least one mounting frame suspension is formed in a gap between the driver unit frame and the mounting frame and extends substantially continuously around the driver unit frame.

Description

[0001] This application claims priority to GB2014020.8 filed on September 7, 2020. Technical Field

[0002] The present invention relates to a dipole loudspeaker for producing bass frequency sounds. Background Art

[0003] Of the frequencies in the audible spectrum, lower frequencies are those that tend to carry the most sound over large distances and are difficult to detect within a room. For example, the nuisance from loud music played nearby is largely low-frequency. "Low" frequencies may also be referred to as "bass" frequencies, and these terms are used interchangeably throughout the literature.

[0004] Many cars today are equipped with a main audio system, which typically consists of a central user interface console with internal or external audio amplifiers and one or more speakers placed in the car's doors. This type of audio system is used to ensure that the same content (such as a broadcast) is loud enough for all passengers.

[0005] Some cars include personal entertainment systems (music, games, and television), which are often equipped with headphones to ensure that each passenger receives personalized sound without disturbing (or being disturbed by) other passengers who are enjoying different audiovisual content.

[0006] However, although the use of headphones ensures good sound quality and a very effective personal sound cocoon (little sound leakage), the use of headphones has safety, ergonomic and comfort issues. Similar considerations apply to other environments, such as homes, studios and public areas, where personal entertainment is desired without disturbing neighbors.

[0007] Some cars include speakers placed very close to a single passenger, so that sound with a sufficiently high sound pressure level (SPL) is available at the ears of the single passenger, while other passengers have a much lower SPL.

[0008] The inventors have observed that the concept of a personal sound cocoon is a useful way to understand methods of placing speakers near a user, where the personal sound cocoon is an area where the user is able to experience sound having an SPL that is considered acceptably high for their enjoyment, while outside the personal sound cocoon the sound is considered to have a lower SPL than within the personal sound cocoon.

[0009] It is known that using highly directional loudspeakers positioned close to individual passengers / users can provide an effective solution for mid-range and high frequencies. However, in most cases it is generally impractical to make loudspeakers directional at bass frequencies, because in order to provide a highly directional loudspeaker for bass frequencies, the size of the radiating surface must be of the same order of magnitude as the wavelength, and for bass frequency content the wavelength is generally very long (e.g. λ = 3.4 m for f = 100 Hz). Loudspeakers with radiating surfaces of this size for producing bass frequencies are impractical in many situations, such as in cars. Despite this, bass frequency content is a very important part of the audio spectrum, and in most music this spectrum represents half or more of the total sound power.

[0010] It is known from WO2019 / 121266A1 that a dipole loudspeaker can provide an effective personal sound cocoon at bass frequencies, effectively providing a personal subwoofer. In particular, WO2019 / 121266A1 explains how the sound produced by the first radiating surface of the diaphragm of such a dipole loudspeaker interferes with the sound produced by the second radiating surface of the diaphragm, and that this interference production can contribute to the beneficial effect of producing a personal sound cocoon at bass frequencies. In particular, for a diaphragm of appropriate size, from a listening position of 40 cm or less from the first radiating surface of such a loudspeaker (e.g. measured along the main radiation axis of the first radiating surface), the user can experience highly localized bass in the sense that the sound pressure level (SPL) experienced by the user will decay rapidly with increasing distance from the loudspeaker.

[0011] Figures 10 and 17 of WO2019 / 121266A1 show such an exemplary dipole loudspeaker, in which the diaphragm is suspended from the drive unit frame via a drive unit suspension, and the drive unit frame itself is suspended from the mounting frame via a mounting frame suspension.

[0012] The present inventors have found that the space inside a car headrest for integrating a bass dipole loudspeaker can be limited due to, for example, design aspects, mechatronics, and further including comfort elements and safety features. Therefore, the present inventors have found that arranging a mounting frame suspension adjacent to and around the periphery of the diaphragm, as exemplified in FIG. 10 of WO 2019 / 121266 A1, would be an inefficient use of the space available inside the car headrest to achieve the desired SPL at the listening position. The present inventors have also found that suspending the drive frame from the mounting legs of the car headrest, as shown in FIG. 17 of WO 2019 / 121266 A1, can lead to a reduction in sound output due to acoustic interference from the first and second radiating surfaces of the diaphragm of the loudspeaker inside the headrest (caused by a short circuit in the sound output), as the available space in the headrest typically presents a "tunnel" in which the bass unit must be mounted.

[0013] The inventors have observed that by providing a second, substantially continuously extending suspension element within the outer contour of the dipole loudspeaker, the space available within a vehicle headrest for implementing a dipole loudspeaker for producing bass frequency sounds can be utilized more efficiently, while preventing undesirable interference of sounds produced by the first and second radiating surfaces of a diaphragm within the headrest.

[0014] The present invention is designed based on the above considerations. Summary of the Invention

[0015] A first aspect of the present invention may provide:

[0016] A dipole loudspeaker assembly for producing bass frequency sounds, the dipole loudspeaker assembly comprising:

[0017] A dipole loudspeaker comprising:

[0018] a diaphragm having a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite surfaces of the diaphragm;

[0019] a drive unit configured to move the diaphragm along the movement axis at bass frequencies so that the first radiating surface and the second radiating surface generate bass frequency sound, wherein the sound generated by the first radiating surface is in opposite phase to the sound generated by the second radiating surface;

[0020] a drive unit frame, wherein the diaphragm is suspended from the drive unit frame via at least one drive unit suspension, wherein the drive unit frame is configured to, in use, allow sound generated by the first radiating surface to propagate out of a first side of the dipole loudspeaker and allow sound generated by the second radiating surface to propagate out of a second side of the dipole loudspeaker; and

[0021] a mounting frame, wherein the drive unit frame (of the dipole loudspeaker) is suspended from the mounting frame via one or more mounting frame suspension members;

[0022] wherein the mounting frame suspension / each mounting frame suspension, when projected onto a plane perpendicular to the axis of motion, at least partially overlaps with one or more elements selected from the group consisting of the diaphragm and the at least one drive unit suspension, when projected onto the same plane;

[0023] Wherein, at least one mounting frame suspension is formed in a gap between the drive unit frame and the mounting frame and extends substantially continuously around the drive unit frame.

[0024] By extending substantially continuously around the driver frame, the at least one mounting frame suspension member can suppress the sound generated by the first radiating surface from reaching the second radiating surface through the gap, and the path length (the distance over which the sound waves generated by the first radiating surface meet the anti-phase sound waves generated by the second radiating surface) is increased because the sound waves are guided around the outer contour of the mounting frame (which may be a headrest in some examples). Consequently, undesirable interference between the sound generated by the first radiating surface and the anti-phase sound generated by the second radiating surface can be reduced, and a higher sound pressure level (SPL) can be achieved at a listening position in front of the first radiating surface.

[0025] By having at least one mounting frame suspension formed in the gap between the drive unit frame and the mounting frame, effective isolation may be provided without increasing the maximum height of the dipole loudspeaker (eg the dimension of the dipole loudspeaker in a direction parallel to the axis of motion).

[0026] By making the mounting frame suspension / mounting frame suspensions at least partially overlap when projected onto a plane perpendicular to the axis of movement and one or more elements selected from the diaphragm and at least one drive unit suspension when projected onto the same plane, the effective radiating surface area of ​​the diaphragm can be increased within a given space, for example within a mounting frame for accommodating a loudspeaker, which may be part of the base of a headrest in a car, for example.

[0027] Moreover, by extending the mounting frame suspension substantially continuously around the drive unit frame, the mounting frame suspension can reduce lateral sway of the diaphragm / drive unit frame in any direction not parallel to the axis of motion, compared to, for example, the configuration shown in FIG. 17 of WO 2019 / 121266 A1.

[0028] For the avoidance of doubt, the mounting frame suspension / each mounting frame suspension, when projected onto a plane perpendicular to the axis of motion, may at least partially overlap with only the diaphragm, only one or more drive unit suspensions, or both the diaphragm and one or more drive unit suspensions, when projected onto the same plane. If there are two or more drive unit suspensions, the mounting frame suspension / each mounting frame suspension may at least partially overlap with one drive unit suspension, or with a plurality (e.g., all) of the drive unit suspensions. If there are two mounting frame suspensions, each mounting frame suspension may at least partially overlap with the same one or more elements, or different one or more elements, selected from the group consisting of the diaphragm and at least one drive unit suspension, when projected onto the same plane.

[0029] Preferably, the phrase "extending substantially continuously around the drive unit frame" is intended to mean that the mounting frame suspension / mounting frame suspensions extend around the drive unit frame with no, few or small interruptions / discontinuities, preferably such that sound generated by the first radiating surface is suppressed, more preferably significantly suppressed, from reaching the second radiating surface via the gap. For example, a large interruption / discontinuity in the mounting frame suspension may mean that the mounting frame suspension provides virtually no suppression effect on sound generated by the first radiating surface from reaching the second radiating surface via the gap, whereas a small or few discontinuities may still allow for a significant suppression effect to be provided.

[0030] The one or more generally continuously extending mounting frame suspensions may thus provide a barrier configured to inhibit sound generated by the first radiating surface from reaching the second radiating surface via the gap.

[0031] The dipole loudspeaker assembly can be used (e.g., configured to be used) in a situation where the user's ears are located at a listening position (preferably, each ear of the user is located at a corresponding listening position), the listening position being in front of the first radiation surface and being 50 cm or less (more preferably 40 cm or less, more preferably 30 cm or less, more preferably 25 cm or less, more preferably 20 cm or less, more preferably 15 cm or less) from the first radiation surface. The terms "user" and "listener" are used interchangeably in the present invention.

[0032] The inventors have observed that, at such a listening position or positions, increasing the effective radiating surface area of ​​the diaphragm results in an improvement in the SPL for the user.

[0033] It should be noted here that although the listening position(s) are defined relative to the front of the first radiating surface, this does not exclude the possibility that a similar effect can be achieved in front of the second radiating surface. In fact, it is expected that a similar effect can be achieved in front of the second radiating surface.

[0034] The dipole loudspeaker assembly can be configured (e.g. by appropriately arranging and sizing the diaphragm, one or more drive unit suspensions and the mounting frame) such that, under free-field conditions, the SPL of a sound produced by the dipole loudspeaker at a bass frequency of 60 Hz (measured along the main radiation axis of the first radiation surface at a distance of 80 cm from the first radiation surface) is at least 30 dB (more preferably at least 25 dB) lower than the SPL of the same sound (measured along the main radiation axis of the first radiation surface at a distance of 10 cm from the first radiation surface).

[0035] In this context, free-field conditions may be understood as anechoic conditions, eg as may be measured in an anechoic chamber.

[0036] In this context, the primary radiation axis of a radiating surface is understood to be the axis along which the radiating surface produces direct sound at maximum amplitude (sound pressure level). Typically, the primary radiation axis will extend outward from the center of the radiating surface. The primary radiation axes of the first and second radiating surfaces will typically extend in opposite directions because they are located on opposite sides of the diaphragm.

[0037] The bass frequencies at which the drive unit is configured to move the diaphragm preferably include frequencies across the range of 60 Hz to 80 Hz, more preferably include frequencies across the range of 50 Hz to 100 Hz, more preferably include frequencies across the range of 40 Hz to 100 Hz, and may include frequencies across the range of 40 Hz to 160 Hz. The drive unit may be configured to move the diaphragm at a frequency not exceeding 250 Hz, 200 Hz, or even 160 Hz in order to ensure that the loudspeaker achieves the desired level of "cocoon formation," as described in WO 2019 / 121266 A1.

[0038] Diaphragm movement at frequencies below 40 Hz may be useful for some applications, but not for others (eg in automobiles, where background noise below 40 Hz tends to be too loud).

[0039] A dipole loudspeaker may thus be (configured as) a subwoofer.A subwoofer may be understood as a loudspeaker dedicated to (rather than adapted for) producing bass frequency sounds.

[0040] The present inventors have discovered that the gap between the driver frame and the mounting frame is preferably minimized in order to maximize the effective radiating surface area of ​​the diaphragm. A certain degree of gap is required to allow the driver to move the diaphragm along its axis of motion at bass frequencies while suspending the driver frame from the mounting frame by at least one mounting frame suspension member.

[0041] Thus, in some examples, at one or more locations around the periphery of the drive unit frame, the gap between the drive unit frame and the mounting frame measured in a plane perpendicular to the axis of motion can be 5 mm or less (more preferably 4 mm or less, more preferably 3 mm or less, more preferably 2 mm or less, and in some cases even 1 mm or less).

[0042] In some examples, the gap between the drive unit frame and the mounting frame measured in a plane perpendicular to the axis of motion can be 5 mm or less, more preferably 3 mm or less, more preferably 2 mm or less, and in some cases even 1 mm or less for at least 50% (more preferably at least 80%, more preferably at least 90%, more preferably at least 95%) of the path extending around the drive unit frame at the periphery of the drive unit frame.

[0043] In some examples, the gap between the drive unit frame and the mounting frame, measured in a plane perpendicular to the axis of motion, can be 5 mm or less, more preferably 3 mm or less, more preferably 2 mm or less, and in some cases even 1 mm or less, for substantially the entire path extending around the drive unit frame at the periphery of the drive unit frame. However, a larger gap may be required at certain areas of the periphery of the drive unit frame, particularly where the mounting frame and / or diaphragm have a non-circular shape (e.g., where the diaphragm has an elliptical or racetrack shape).

[0044] In some examples, the first and second radiating surfaces of the diaphragm may have circular shapes.

[0045] In other examples, the first and second radiating surfaces of the diaphragm can have non-circular shapes, such as elliptical, rectangular, square, rounded rectangular, or racetrack shapes. This can help maximize the effective radiating surface area of ​​the diaphragm within other design constraints (e.g., integrating the speaker into a car headrest).

[0046] The present inventors have discovered that the size and shape of the mounting frame can be varied depending on the shape and size of the available space (e.g., the space available in a headrest) in which the loudspeaker is to be mounted. Accordingly, the shape of the diaphragm (and in particular the first and second radiating surfaces of the diaphragm) can be selected to closely match the shape of the space provided by the mounting frame, for example, so that the gap between the mounting frame and the driver unit frame is minimized along a path extending around the driver unit frame at its periphery.

[0047] The dipole loudspeaker assembly may include a plurality of dipole loudspeakers, wherein a drive unit frame of each loudspeaker is suspended from a mounting frame via one or more mounting frame suspension members. Each dipole loudspeaker may have features according to the definition of a dipole loudspeaker provided herein. For example, each dipole loudspeaker may include:

[0048] a diaphragm having a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite surfaces of the diaphragm;

[0049] a drive unit configured to move the diaphragm along the movement axis at bass frequencies so that the first radiating surface and the second radiating surface generate bass frequency sound, wherein the sound generated by the first radiating surface is in opposite phase to the sound generated by the second radiating surface;

[0050] A drive unit frame, wherein the diaphragm is suspended from the drive unit frame via at least one drive unit suspension, wherein the drive unit frame is configured to, in use, allow sound produced by the first radiating surface to propagate out of a first side of the dipole loudspeaker and allow sound produced by the second radiating surface to propagate out of a second side of the dipole loudspeaker.

[0051] The effective radiation area of ​​the first radiation surface (or the combined effective radiation area of ​​the first radiation surfaces if more than one dipole loudspeaker is included in the dipole loudspeaker assembly) may be 60 cm 2 or larger, more preferably 80cm 2 or larger, more preferably 100 cm 2 For reasons that can be understood from WO 2019 / 121266 A1, the effective radiation area in this range can provide an effective personal sound cocoon zone at bass frequencies.

[0052] As is known in the art, for a o and inner diameter d i A diaphragm having a circular perimeter (e.g., Figure 1 a to Figure 1 c), the effective radiation surface area of ​​the diaphragm can be estimated as Where d is the semi-diameter of the roll suspension, (d o +d i ) / 2.

[0053] Alternatively, or for more complex diaphragm geometries, the effective radiating area SD of the diaphragm can be measured using known techniques, see for example “Dynamical Measurement of the Effective Radiating area SD”, Klippel GmbH (https: / / www.klippel.de / fileadmin / klippel / Files / Know_How / Application_Notes / AN_32_Effective_Radiation_Area.pdf).

[0054] To avoid complex calculations regarding the effective radiating area, the surface area of ​​the first radiating surface (or the combined surface area of ​​the first radiating surfaces if more than one dipole loudspeaker is included in the dipole loudspeaker assembly) may be 50 cm 2 or larger, 60cm 2 or larger, more preferably 80cm 2 or larger, more preferably 90 cm 2 For surface areas within these ranges, an effective personal sound cocoon at bass frequencies can be achieved for reasons that can be understood from WO 2019 / 121266 A1 (note that the effective radiation area is typically only a few % larger than the actual surface area).

[0055] The diaphragm can take various forms.

[0056] For example, the membrane may be paper or another sheet material.

[0057] For example, the membrane may be a single (monolithic) sheet of material. This material is preferably lightweight, for example having a mass of 0.1 g / cm 3 or less. The material may be extruded polystyrene or the like. In some examples, the membrane may be covered by a surface layer, for example to protect the membrane. For example, the surface layer may be paper, carbon fiber, or plastic foil.

[0058] For example, the membrane may comprise several sheets of material attached together, for example by glue. For example, the membrane may comprise a first cone and a second cone, wherein the first cone and the second cone are glued back to back. The first cone and the second cone may be made of paper, for example.

[0059] The diaphragm may comprise one or more (e.g. a pattern of) pleats (most suitable if the diaphragm is a sheet material, such as paper). This may help to reduce the height of the dipole loudspeaker (e.g. in a direction parallel to the axis of motion) while still maintaining a stable dipole loudspeaker. The pleats / pleats extend radially between the inner peripheral edge and the outer peripheral edge of the diaphragm when viewed in the circumferential direction. The pleats / pleats may have a depth that increases from the outer peripheral edge and the inner peripheral edge of the diaphragm towards a base region positioned between the outer peripheral edge and the inner peripheral edge of the diaphragm (e.g. approximately in the middle between the outer peripheral edge and the inner peripheral edge of the diaphragm). Thus, the maximum depth of the pleats / pleats may be located at the base region. The pleats / pleats may be provided with a corresponding surface in the base region. Examples of possible pleat patterns are described in WO2005 / 015950A1.

[0060] The at least one drive unit suspension may include a roll suspension.The roll suspension may interconnect the drive unit frame and the peripheral edge of the diaphragm.

[0061] At least one drive unit suspension element may include a damper. The damper may be secured to the drive unit frame at its inner edge and to the diaphragm at its outer edge. Alternatively, the damper may be secured to the drive unit frame at its outer edge and to the diaphragm at its inner edge. The damper may be understood as a fabric ring having circumferentially extending corrugations. The damper may facilitate movement of the diaphragm along the axis of motion while inhibiting, and preferably substantially preventing, movement of the diaphragm perpendicular to the axis of motion.

[0062] If the diaphragm includes one or more pleats (see above), the damper may be fixed at its inner edge to the drive unit frame and at its outer edge to the surface of the pleats at the base area of ​​the diaphragm, preferably by means of an adhesive such as glue. Alternatively, the damper may be fixed at its outer edge to the drive unit frame and at its inner edge to the surface of the pleats at the base area of ​​the diaphragm, preferably by means of an adhesive such as glue. Optionally, the diaphragm may be suspended from the drive unit frame by means of multiple dampers.

[0063] If the diaphragm comprises one or more corrugations (see above), the dipole loudspeaker may comprise a reinforcing element which extends around the magnet unit of the drive unit and reinforces the diaphragm at one or more base regions of the diaphragm so as to strengthen the diaphragm against deformation in the one or more base regions. The reinforcing element may be circular and, when viewed in cross section, may comprise corrugations to reinforce the base region. For example, the reinforcing element may be made of a material selected from the group consisting of paper, aluminum, titanium, polypropylene, polycarbonate, acrylonitrile butadiene styrene or Kevlar. TM The reinforcement element may be attached to the middle region of the membrane (directly) or indirectly via a spring, preferably by means of an adhesive. Examples of possible reinforcement elements are described in WO 2008 / 135857 A1.

[0064] The at least one mounting frame suspension member can be configured to have a resonant frequency below the frequency spectrum in which the dipole loudspeaker is configured to operate (e.g., below 40 Hz), for example, to limit forces on the support structure (e.g., the mounting frame). However, the resonant frequency of the at least one mounting frame suspension member is preferably no less than 10 Hz, as at least one mounting frame suspension member having a resonant frequency below 10 Hz can cause static deflection (Xstat) issues as described below.

[0065] Reference herein to the "resonant frequency" of the at least one mounting frame suspension refers to the frequency at which, in use, a mass suspended from the mounting frame by the at least one mounting frame suspension resonates.

[0066] Thus, at least one mounting frame suspension may be configured to have a resonant frequency between 10 Hz and 30 Hz (inclusive), more preferably between 10 Hz and 20 Hz (inclusive).

[0067] The at least one mounting frame suspension may be configured such that a static deflection of the at least one mounting frame suspension at an angle α of 90° is 2.5 mm or less, more preferably 1.5 mm or less. The at least one mounting frame suspension may be configured such that a static deflection of the at least one mounting frame suspension at an angle α of 90° is 0.5 mm or more.

[0068] Herein, α is the angle between a plane perpendicular to the primary radiating axis and the vertical, and the "static deflection" of at least one mounting frame suspension is the distance a mass suspended from the mounting frame by the at least one mounting frame suspension deviates from a rest position, wherein the rest position is defined as the position of the mass at α = 0°.

[0069] If there is only a single mounting frame suspension, the single mounting frame suspension may be configured to be positioned in the center of gravity plane when the diaphragm is at rest.

[0070] Herein, the centroid plane is defined as the plane perpendicular to the axis of motion containing the centroid (defined as M1 below) of the dipole loudspeaker.

[0071] The drive unit frame may be suspended from the mounting frame via at least two mounting frame suspensions, wherein the at least two mounting frame suspensions are spaced apart in a direction parallel to the axis of motion.

[0072] Providing at least two mounting frame suspensions, each of which extends substantially continuously around the drive unit frame, can improve the stability of the dipole loudspeaker.

[0073] Where there are two mounting frame suspensions separated in a direction parallel to the axis of motion, the respective mounting frame suspensions may be configured to be positioned on opposite sides of the center of gravity plane (preferably also equidistant from the center of gravity plane in a direction parallel to the axis of motion) when the diaphragm is at rest.

[0074] The drive unit frame may be integral (ie, integrally formed) with the one or more mounting frame suspensions. In other words, the drive unit frame and the one or more mounting frame suspensions may be formed as a single piece.

[0075] Alternatively, the one or more mounting frame suspensions may be configured to be attached to the drive unit frame, for example, by one or more snap connections, by an adhesive (e.g., glue beads, self-adhesive tape), and / or by a friction fit. For example, the drive unit frame and the one or more mounting frame suspensions may have corresponding and interlocking snap elements for snapping the drive unit frame to the one or more mounting frame suspensions.

[0076] The drive unit frame may be provided in one or more pieces that are configured to be attached (e.g. snap-fitted) together to form the drive unit frame. For example, the drive unit frame may include one or more auxiliary frames that are configured to be attached (e.g. snap-fitted) to one or more other pieces of the drive unit frame in order to form the drive unit frame. The one or more auxiliary frames of the drive unit may be configured to separate two mounting frame suspensions, e.g. two roll suspensions (see below), in a direction parallel to the axis of motion. The one or more auxiliary frames of the drive unit may be attached to the two mounting frame suspensions, e.g. by an adhesive (e.g. glue beads, self-adhesive tape) and / or by a friction fit.

[0077] The mounting frame may be integral (eg, integrally formed) with one or more mounting frame suspensions. In other words, the mounting frame and one or more mounting frame suspensions may be formed as a single piece.

[0078] Alternatively, one or more mounting frame suspensions may be configured to attach to the mounting frame, for example, via one or more snap connections, via an adhesive (e.g., glue beads, self-adhesive tape), and / or via a friction fit. For example, the mounting frame and the one or more mounting frame suspensions may have corresponding, interlocking snap elements for snapping the mounting frame to the one or more mounting frame suspensions. This may be applicable, for example, to mounting frame suspensions that are blocks of resilient material (see below).

[0079] The mounting frame may be provided in one or more pieces that are configured to be attached (eg, snap-fit) together to form the mounting frame.

[0080] For example, the mounting frame can include one or more auxiliary frames (described below) that are configured to be attached (e.g., snap-fit) to one or more other members of the mounting frame to form the mounting frame. The one or more auxiliary frames of the mounting frame can be configured to separate two mounting frame suspensions, such as two roll suspensions (see below), in a direction parallel to the axis of motion. The one or more auxiliary frames of the mounting frame can be attached to the two mounting frame suspensions, for example, by an adhesive (e.g., glue beads, self-adhesive tape) and / or by a friction fit.

[0081] In this way, the drive unit frame and therefore the diaphragm can be assembled more easily in the mounting frame.

[0082] Optionally, the drive unit frame may include one or more protruding flanges. These protruding flanges may facilitate manufacturing, in particular facilitating the adhering of one or more mounting frame suspensions to the mounting frame.

[0083] The / each mounting frame suspension may comprise a roll suspension.

[0084] In some examples, there are two mounting frame suspensions, each of which is a roll suspension. The two roll suspensions can be separated in a direction parallel to the axis of motion by a portion of the mounting frame and / or a portion of the drive unit frame. Specifically, the two roll suspensions can be separated in a direction parallel to the axis of motion by one or more auxiliary frames of the mounting frame and / or one or more auxiliary frames of the drive unit frame. Specifically, the two roll suspensions can be separated in a direction parallel to the axis of motion by a pair of auxiliary frames, the first of which is part of the mounting frame and the second of which is part of the drive unit frame. Using two roll suspensions arranged in this manner helps provide increased stability against sway (e.g., in a direction not parallel to the axis of motion). Each roll suspension can comprise, for example, rubber, pressed or non-pressed foam, and / or fabric. Each roll suspension can comprise an elastic material or a non-elastic material. Each roll suspension can extend substantially continuously around the drive unit frame.

[0085] Optionally, if there is more than one mounting frame suspension (e.g., two roll suspensions), one of the mounting frame suspensions may include one or more pressure equalization vents (e.g., one roll suspension may be perforated). Alternatively / additionally, the mounting frame and / or the drive unit frame itself may include one or more pressure equalization vents. This may help avoid pressure buildup in the space between the two mounting frame suspensions.

[0086] In some examples, one or more mounting frame suspensions (optionally, the mounting frame suspension / s) may include a sheet of elastic material held taut between the mounting frame and the drive unit frame. The mounting frame and the drive unit frame may be configured to hold the sheet / s of elastic material such that there is little or no slack in the sheet / s of elastic material and such that the elastic material is substantially unstretched when the diaphragm is at rest. Specifically, the mounting frame suspension / s may include a sheet of elastic material held taut between a subframe of the mounting frame and the drive unit frame, respectively. The sheet / s of elastic material may include, for example, elastic foam or (silicone) rubber.

[0087] The inventors have observed that the roll suspension allows axial movement due to excess material in the roll suspension that can "tilt away" during drift. It follows that the roll suspension need not be elastic. Instead, when the mounting frame suspension / mounting frame suspensions comprise one or more taut sheets of elastic material held between the mounting frame and the drive unit frame (e.g., so that there is no excess material or slack), elasticity is required to provide compliance to the suspension. It will be appreciated that such elasticity can also prevent rocking of the drive unit frame and diaphragm (e.g., in directions not parallel to the axis of motion), as such rocking would be detrimental to the elastic bias of the material. Consequently, only a single taut sheet of elastic material may be required to adequately reduce rocking.

[0088] Preferably, the mounting frame and the drive unit frame (e.g., the auxiliary frame of the mounting frame and the auxiliary frame of the drive unit plane) overlap when projected onto a plane perpendicular to the axis of motion, so that the mounting frame serves to prevent the drive unit frame (and in particular the magnet unit attached thereto) from being ejected from the mounting frame in the event of a collision or another event involving sudden deceleration of the loudspeaker. The overlapping portion of the mounting frame and the drive unit frame is preferably rigid.

[0089] In some examples, one or more mounting frame suspensions (optionally, the mounting frame suspension / each mounting frame suspension) may include a block of resilient material. The block may be a foam block, such as a non-pressed resilient foam block. The resilient block may be solid or hollow. The resilient block may include one or more corrugations and / or cavities, which may help increase the stability of the block / each block used as a mounting frame suspension.

[0090] For the avoidance of any doubt, if the loudspeaker comprises a plurality of mounting frame suspensions, each mounting frame suspension may be of the same type as described above. Alternatively, each or some mounting frame suspensions may be of a different type than described above.

[0091] In the context of the present invention, the term "drive unit frame" is intended to encompass any substantially rigid structure from which a diaphragm may be suspended.

[0092] In the context of the present invention, the term "mounting frame" is intended to encompass any substantially rigid structure from which the drive unit frame of a loudspeaker can be suspended.

[0093] The mounting frame may define a waveguide that at least partially (and preferably completely) surrounds the diaphragm and is configured to direct sound generated by the first and / or second radiating surfaces of the diaphragm out of opposite sides of the mounting frame. The waveguide may optionally be formed (partially or completely) of foam. If the speaker assembly is a seat assembly (see below), the waveguide may be located in the seat headrest.

[0094] The drive unit may be an electromagnetic drive unit comprising a magnet unit configured to generate a magnetic field and a voice coil attached to the diaphragm (e.g., via a voice coil connector). The magnet unit may be rigidly attached to the drive unit frame. In use, the voice coil may be excited (by passing a current through it) to generate a magnetic field that interacts with the magnetic field generated by the magnet unit and causes the voice coil (and therefore the diaphragm) to move relative to the magnet unit. The magnet unit may comprise a permanent magnet. The magnet unit may further comprise a yoke (e.g., a U-shaped yoke) and a steel washer (or a steel top plate). The magnet unit may be configured to provide an air gap and may be configured to provide a magnetic field in the air gap. Specifically, the air gap may be provided between the permanent magnet and the yoke, the permanent magnet being located radially inside the air gap relative to a direction parallel to the axis of motion, and the yoke being located radially outside the air gap relative to a direction parallel to the axis of motion. The voice coil may be configured to be located in the air gap when the diaphragm is stationary. Such drive units are well known.

[0095] In the present invention, a voice coil may be understood as a coiled length of wire attached to a diaphragm.The voice coil may be considered distinct from any (typically non-coiled) electrical connections (e.g. wires) used to supply electrical energy to the voice coil.

[0096] The magnet unit may be located in front of the second radiating surface of the diaphragm. The loudspeaker may include a safety element located between the magnet unit and the second radiating surface of the diaphragm. The safety element may be configured to prevent the magnet unit from passing through the diaphragm, for example, in the event of a collision or another event involving sudden deceleration of the loudspeaker (e.g., if the loudspeaker has moved in the direction of the main radiation axis of the first radiating surface). The safety element is preferably rigid. The safety element may also function as a voice coil coupler as described below.

[0097] Such a safety element may be particularly useful if the loudspeaker is mounted in a vehicle seat headrest, as it may help to provide protection to a person seated in such a seat in the event of a vehicle collision.

[0098] The loudspeaker may include a voice coil coupler, optionally attached to the diaphragm at its inner peripheral edge, preferably to the second radiating surface of the diaphragm. The voice coil coupler may include a tubular element. The voice coil may be attached to the diaphragm by wrapping around the tubular element of the voice coil coupler. As described above, the voice coil coupler may also serve as a safety element.

[0099] The voice coil coupling may comprise ribs which extend radially outwards from the tubular element of the voice coil coupling through slots in the yoke (the yoke may therefore be referred to as a slotted yoke).This allows the loudspeaker to have a small overall height.

[0100] Preferably, the ribs of the voice coil coupler extend into the interior of the diaphragm. This can help reinforce the diaphragm, particularly if the diaphragm has a thickness (in the direction of the axis of motion) of 15 mm or less, or 10 mm or less, as at such thicknesses, reinforcement of the diaphragm may be more desirable, particularly if the diaphragm is formed from a lightweight material such as extruded or expanded foam of polypropylene (PP), polyurethane (PU), or polystyrene (PS).

[0101] The diaphragm may have a thickness of 5 mm or more. If the diaphragm is formed from a lightweight material such as extruded or expanded foam of polypropylene (PP), polyurethane (PU) or polystyrene (PS), a thickness of 5 mm or more may be required.

[0102] Preferably, the ribs extending into the body of the diaphragm are plates. The ribs are preferably made of a rigid, lightweight material. The ribs are preferably made of a non-conductive (non-electrically conductive) material (e.g., balsa wood) to avoid interference with the magnet unit and to prevent heat transfer from the voice coil to the diaphragm (particularly where the diaphragm is formed of a lightweight material such as extruded or expanded foam, as the voice coil can heat up during operation and these foam materials are generally not able to withstand significant amounts of heat).

[0103] The slots may extend in a direction parallel to the axis of motion.There may be three or more ribs and three or more slits, for example, wherein each rib extends through a respective slit.

[0104] The ribs may extend into the interior of the membrane.This may be particularly suitable if the membrane is a solid block of a material, preferably a lightweight material, such as a foam of polypropylene (PP), polyurethane (PU) or polystyrene (PS).

[0105] This strengthens and reinforces the lightweight foam membrane, which can be fragile on its own.

[0106] Each rib can be a rigid, lightweight, non-conductive rib. Each rib can be a plate. For example, each rib can include balsa wood.

[0107] Optionally, the permanent magnet and the yoke are configured such that the magnetic flux density in the air gap reaches a first local maximum peak position along a direction parallel to the axis of motion and reaches a second local maximum peak position along the direction parallel to the axis of motion, wherein the first peak position and the second peak position are spatially separated by a valley region in the direction parallel to the axis of motion, wherein the magnetic flux density in the valley region is lower than both the first local maximum and the second local maximum, wherein the voice coil is configured to be positioned in the valley region when the diaphragm is stationary. This can allow for a large practical excursion while using a magnet unit having a small height.

[0108] To achieve this magnetic flux density, the steel washer (or steel top plate) of the magnet unit may include a recess (e.g., a cutout) at a position parallel to the axis of motion, which is adjacent to (e.g., near) the voice coil when the diaphragm is stationary. The cutout may accommodate a short-circuit ring (e.g., a conductive ring configured to dissipate eddy currents). The short-circuit ring may include, for example, copper. Examples are provided in PCT / EP2020 / 064577.

[0109] The speaker may include a flexible dust cover. The flexible dust cover may be attached to the tubular voice coil coupler. The dust cover may also be attached to the diaphragm. An exemplary flexible dust cover is discussed in WO2019 / 121072.

[0110] The dipole loudspeaker according to the first aspect of the invention may find use in any application where it is desired to provide a personal sound cocoon.

[0111] In some examples, the dipole speaker assembly may be a dipole speaker module configured to be mounted in a seat headrest.

[0112] The dipole speaker module preferably includes one or more attachment structures on a mounting frame, wherein the attachment structures are configured to attach the mounting frame to a seat headrest (preferably, a rigid structure of a headrest, such as a support foam area of ​​an automobile headrest, a rigid frame of a headrest, or a combination of a support foam area and a rigid frame of a headrest), thereby mounting the dipole speaker module in the seat headrest.

[0113] The dipole loudspeaker module may comprise a first protective grille positioned in front of the first radiating surface of the diaphragm.The first protective grille may, for example, be attached to or form part of the mounting frame.

[0114] The first protection grid may help protect the dipole loudspeaker, for example, as described below with reference to Figure 11G Described in more detail.

[0115] When the dipole speaker module is mounted in a headrest, the first protective grille may be shaped to follow the contours of a surrounding area of ​​the headrest (eg, a surrounding foam area of ​​the headrest).

[0116] The first protective grille can be configured to be covered with open-cell foam to provide a desired headrest shape when the first protective grille is covered with open-cell foam (preferably a uniform thickness of open-cell foam). If the dipole speaker module is installed in a seat headrest (see below), and the first protective grille is shaped to follow the contour of the surrounding area of ​​the headrest (see above), then the first protective grille and at least a portion of the surrounding area of ​​the headrest can be covered with a uniform thickness of open-cell foam. The contours of the first protective grille and the surrounding area of ​​the headrest can be shaped relative to each other so that the desired headrest shape is achieved when the first protective grille and at least a portion of the surrounding area of ​​the headrest are covered with a uniform thickness of open-cell foam.

[0117] The dipole loudspeaker module may comprise a second protective grille positioned in front of the second radiating face of the diaphragm.The second protective grille may, for example, be attached to or form part of the mounting frame.

[0118] The second protection grid can help protect the dipole loudspeaker, for example, as described below with reference to Figure 11G Described in more detail.

[0119] When the dipole speaker module is mounted in a headrest, the second protective grille may be shaped to follow the contours of a surrounding area of ​​the headrest (eg, a surrounding foam area of ​​the headrest).

[0120] The second protective grille can be configured to be covered with open-cell foam to provide a desired headrest shape when the first protective grille is covered with open-cell foam (preferably a uniform thickness). If the dipole speaker module is installed in the seat headrest (see below), and the second protective grille is shaped to follow the contours of the headrest's surrounding area (see above), the second protective grille and at least a portion of the headrest's surrounding area can be covered with a uniform thickness of open-cell foam. The contours of the second protective grille and the headrest's surrounding area can be shaped relative to each other so that the desired headrest shape is achieved when the second protective grille and at least a portion of the headrest's surrounding area are covered with a uniform thickness of open-cell foam.

[0121] In a second aspect, a seat assembly may be provided, comprising:

[0122] a chair for seating a user; and

[0123] A dipole loudspeaker assembly according to the first aspect.

[0124] Preferably, the dipole loudspeaker is mounted in the seat headrest.

[0125] In some examples, the dipole speaker assembly can be mounted in a seat headrest. For example, the dipole speaker assembly can be a dipole speaker module (described above) mounted in a seat headrest.

[0126] In some examples, the entire seat assembly can function as a dipole speaker assembly, wherein the speaker's mounting frame is the rigid frame of the seat. In other words, the speaker assembly can be a seat assembly comprising a seat for seating a user, wherein the speaker's mounting frame is the rigid frame of the seat.

[0127] For the avoidance of any doubt, the rigid frame of the chair may include one or more areas of support foam.

[0128] The chair can be constructed to position a user sitting in the chair so that at least one ear of the user is located at a listening position (preferably each ear of the user is located at a corresponding listening position) 40 cm or less (more preferably 30 cm or less, more preferably 25 cm or less, more preferably 20 cm or less, more preferably 15 cm or less) from the first radiating surface of the speaker.

[0129] Preferably, the dipole loudspeaker is mounted within a headrest of the seat ("seat headrest"). Since typical headrests are constructed to be a small distance (e.g. 30 cm or less) from one or both ears of a user seated in the seat, this is a particularly convenient way of constructing the seat to position a user seated in the seat so that the user's ears are located in a listening position a small distance (e.g. 30 cm or less) from the first radiating surface of the loudspeaker. The headrest is detachable from the rest of the seat. For example, the headrest may include mounting pins that are part of the rigid frame of the seat but are constructed to allow the headrest to be detached from the rest of the rigid frame of the seat (such mounting pins are common in most cars). Alternatively, the headrest may be integral with the rest of the seat.

[0130] If more than one dipole speaker is included in the speaker assembly (see above), each dipole speaker may be mounted within the seat headrest.

[0131] A seat headrest typically has a front surface configured to face the head of a user seated in the seat and a rear surface configured to face away from the head of the user seated in the seat. The dipole speaker is preferably mounted within the seat headrest, e.g., with a first radiating surface of the speaker facing the front surface of the headrest, e.g., with a major axis of the first radiating surface extending through the front surface of the headrest.

[0132] The dipole speaker can be mounted in a seat headrest so that the seat headrest is configured to allow sound generated by the first radiating surface of the diaphragm to propagate out through the front surface of the headrest, and to allow sound generated by the second radiating surface of the acoustic radiator to propagate out through the rear surface of the headrest. The seat headrest can include an acoustically transparent region (e.g., acoustically transparent foam) for this purpose.

[0133] A skilled artisan will appreciate that the extent to which a seat headrest is configured to allow sound generated by the first radiating surface of the diaphragm to radiate out through the front surface of the headrest and to allow sound generated by the second radiating surface of the diaphragm to radiate out the rear surface of the headrest will depend on a number of factors, such as the desired level of personal vocal cocoon formation, the desired size of the personal vocal cocoon, and other design considerations (e.g., implementing a speaker in a car headrest may require some of the frame or other structure to be located in front of the first and / or second radiating surfaces). Therefore, the extent to which the seat headrest should open toward the first and second radiating surfaces cannot be easily defined in a precise manner.

[0134] The seat assembly may include one or more additional speakers, such as one or more, preferably two or more directional mid-high frequency speakers, which operate, for example, in a frequency band including 300 Hz to 3 kHz, more preferably 150 Hz to 20 kHz. Specifically, in addition to a dipole speaker (for generating bass frequencies), the seat headrest may also include one or more, preferably two or more directional mid-high frequency speakers. The one or more directional mid-high frequency speakers may be included in the front wing of the headrest. The one or more directional mid-high frequency speakers may be of a cardioid type, such as described in GB2004076.2, but other forms of directional speakers are of course possible.

[0135] The seat may be a vehicle seat, for use in a vehicle such as a car ("car seat") or an airplane ("aircraft seat").

[0136] The seat may be a seat for use outside a vehicle, for example, a seat for a computer game player, a seat for studio monitoring, or a seat for home entertainment.

[0137] In a third aspect, there may be provided a vehicle (eg, a car or an airplane) having a plurality of seat assemblies as described in conjunction with the first aspect of the invention.

[0138] In a fourth aspect, a method of manufacturing a dipole loudspeaker assembly according to the first aspect of the present invention is provided. The method may include snapping together two or more components of the loudspeaker assembly, such as snapping one or more mounting frame suspensions to a drive unit frame, snapping one or more mounting frame suspensions to a mounting frame, snapping an auxiliary frame (or other component of a drive unit frame) to another component of the drive unit frame, and snapping the auxiliary frame (or other component of the mounting frame) to another component of the mounting frame.

[0139] In a fifth aspect, there is provided a dipole loudspeaker according to the first aspect of the present invention, wherein the drive unit frame of the dipole loudspeaker is configured to be suspended from the mounting frame via one or more mounting frame suspension members.

[0140] The dipole loudspeaker may include any of the features described above in connection with the first aspect of the invention without the dipole loudspeaker being actually suspended from the mounting frame via one or more mounting frame suspension members.

[0141] The dipole loudspeaker may comprise one or more mounting frame suspensions (eg as defined in relation to the first aspect of the invention) for the purpose of suspending the drive unit frame (of the dipole loudspeaker) from the mounting frame via the one or more mounting frame suspensions.

[0142] The dipole loudspeaker may comprise an auxiliary frame of mounting frame suspensions (such as defined in relation to the first aspect of the invention) for the purpose of suspending the drive unit frame (of the dipole loudspeaker) from the mounting frame via one or more mounting frame suspensions.

[0143] In a sixth aspect, a speaker is provided, comprising:

[0144] a diaphragm having a first radiating surface facing forward and a second radiating surface facing backward, the first radiating surface being configured to generate sound to be radiated outward from the speaker in a forward direction, wherein the first radiating surface and the second radiating surface are located on opposite sides of the diaphragm;

[0145] A drive unit configured to move the diaphragm along the motion axis, the drive unit comprising:

[0146] a magnet unit configured to provide a magnetic field in an air gap, wherein the air gap is located between a permanent magnet of the magnet unit and a yoke of the magnet unit, the permanent magnet is located radially inside the air gap with respect to a direction parallel to the motion axis, and the yoke is located radially outside the air gap with respect to the direction parallel to the motion axis; and

[0147] a voice coil configured to be positioned in the air gap when the diaphragm is at rest;

[0148] wherein the voice coil is attached to the diaphragm via a voice coil coupler, wherein the voice coil coupler includes a rib extending radially outward from the voice coil coupler through a slot in the yoke, and wherein the rib extends to an interior of the diaphragm.

[0149] The loudspeaker of the sixth aspect may include any one or more of the features mentioned above in relation to any of the preceding aspects of the invention, except where such a combination is expressly impermissible or expressly avoided.

[0150] For example, the diaphragm may have a thickness (in the direction of the axis of motion) of 15 mm or less, or 10 mm or less. The diaphragm may have a thickness of 5 mm or more.

[0151] For example, the membrane may be formed from a lightweight material such as extruded or expanded foam of polypropylene (PP), polyurethane (PU) or polystyrene (PS).

[0152] For example, the ribs may be plates.

[0153] For example, the ribs are preferably made of a non-conductive (non-electrically conductive) material (such as balsa wood) to avoid interfering with the magnet unit and prevent heat transfer from the voice coil to the diaphragm (these foam materials cannot withstand large amounts of heat, and the voice coil may become hot during operation).

[0154] For example, the speaker may be a dipole speaker for producing bass frequency sounds, wherein the dipole speaker is configured, in use, to allow sound produced by a first radiating surface to propagate out of a first side of the dipole speaker, and to allow sound produced by a second radiating surface to propagate out of a second side of the dipole speaker.

[0155] For example, the loudspeaker may comprise a drive unit frame, wherein the diaphragm is suspended from the drive unit frame via at least one drive unit suspension.The magnet unit may be rigidly attached to the drive unit frame.

[0156] For example, the loudspeaker may be included in a loudspeaker assembly comprising a mounting frame, wherein a drive unit frame (of the loudspeaker) is suspended from the mounting frame via one or more mounting frame suspensions. The mounting frame suspension / s when projected onto a plane perpendicular to the axis of motion may at least partially overlap with the diaphragm and / or one or more drive unit suspensions when projected onto the same plane. The at least one mounting frame suspension may be formed in a gap between the drive unit frame and the mounting frame and may extend substantially continuously around the drive unit frame.

[0157] Although the loudspeaker of the sixth aspect may be a dipole loudspeaker configured in accordance with the first aspect of the invention (eg as exemplified herein), the skilled person will appreciate that this is not necessarily the case.

[0158] Specifically, the speaker of the sixth aspect does not need to be configured as a dipole speaker. For example, the speaker of the sixth aspect may include a housing configured to suppress the sound generated by the second radiating surface from propagating out of the speaker, i.e., to enable the speaker to act as a traditional monopole speaker.

[0159] The speaker according to the sixth aspect also does not need to be configured as a woofer even though it is exemplified below.

[0160] The present invention includes any combination of the described aspects and preferred features unless such a combination is clearly infeasible or expressly avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0161] Examples and experiments illustrating the principles of the present invention will now be discussed with reference to the accompanying drawings, in which:

[0162] Figure 1 A cross-sectional view of an exemplary dipole loudspeaker assembly is shown.

[0163] Figure 2A Shown Figure 1 A perspective view of an exemplary dipole loudspeaker assembly.

[0164] Figure 2B Shown Figure 1 Another perspective view of an exemplary dipole loudspeaker assembly.

[0165] Figure 2C Shown Figure 1 Another cross-sectional view of an exemplary dipole loudspeaker assembly.

[0166] Figures 3A to 3H Different exemplary mounting frame suspension arrangements are shown.

[0167] Figure 4 A cross-sectional view of another exemplary dipole loudspeaker assembly is shown.

[0168] Figure 5 A cross-sectional view of another exemplary dipole loudspeaker assembly is shown.

[0169] Figure 6 A cross-sectional view of another exemplary dipole loudspeaker assembly is shown.

[0170] Figure 7 A cross-sectional view of another exemplary dipole loudspeaker assembly is shown.

[0171] Figure 8A Shown included in Figure 7 A perspective view of the dipole speaker in the dipole speaker assembly.

[0172] Figure 8B Shown included in Figure 7 Another perspective view of the dipole loudspeaker in the dipole loudspeaker assembly.

[0173] Figures 9A to 9C An exemplary dipole speaker assembly is shown where the speaker is incorporated into a headrest.

[0174] Figures 10A to 10H Technical considerations for designing a loudspeaker for use in a loudspeaker assembly are illustrated.

[0175] Figures 11A to 11G Another dipole loudspeaker assembly for producing bass frequency sounds is shown. DETAILED DESCRIPTION

[0176] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying drawings. Other aspects and embodiments will be apparent to those skilled in the art. All documents mentioned herein are incorporated herein by reference.

[0177] Figure 1 1 is a cross-sectional view of a dipole speaker assembly 100 for producing bass frequency sounds. The dipole speaker assembly 100 includes a dipole speaker 101, which includes a diaphragm 110, a driver unit 120, and a driver unit frame 130. The dipole speaker assembly 100 also includes a mounting frame 140, which is mounted on the Figure 1 Only partially shown.

[0178] Figure 2A and Figure 2B yes Figure 1 A perspective view of the dipole loudspeaker assembly 100 is shown. Figure 2A The first side 104 of the dipole loudspeaker assembly 100 is shown. Figure 2B An opposing second side 106 of the dipole loudspeaker assembly 100 is shown.

[0179] Figure 2C yes Figure 1 FIG. 1 is a cross-sectional perspective view of a dipole loudspeaker assembly 100 .

[0180] Mounting frame 140 Figures 2A to 2C 146b, which will be explained in more detail below).

[0181] The diaphragm 110 of the dipole loudspeaker 101 has a first radiating surface 112 and a second radiating surface 114 , wherein the first radiating surface 112 and the second radiating surface 114 are located on opposite surfaces of the diaphragm 110 .

[0182] The driver 120 is configured to move the diaphragm 110 along the movement axis at bass frequencies 102, so that the first radiating surface 112 and the second radiating surface 114 generate bass frequency sounds. The sound generated by the first radiating surface 112 and the sound generated by the second radiating surface 114 are in opposite phases.

[0183] In this example, the diaphragm 110 is suspended from the drive unit frame 130 via two drive unit suspensions 132, 166. In use, the dipole loudspeaker 100 is configured to allow sound generated by the first radiating surface 112 to propagate out of a first side 104 of the dipole loudspeaker, and to allow sound generated by the second radiating surface 114 to propagate out of a second side 106 of the dipole loudspeaker 100 (e.g., via one or more gaps 150 in the drive unit frame 130).

[0184] exist Figure 1 In the example shown, the diaphragm 110 is made of paper, and the two drive unit suspensions 132 , 166 are a roll suspension 132 and a spider 166 , respectively, that extend substantially continuously around the periphery of the diaphragm 110 .

[0185] The drive unit frame 130 is suspended from the mounting frame 140 via two mounting frame suspensions in the form of roll suspensions 142a, 142b. The two mounting frame suspensions 142a, 142b (respectively) are formed in the gap between the drive unit frame 130 and the mounting frame 140 and extend generally continuously around the drive unit frame 130.

[0186] The two mounting frame suspensions 142a, 142b, when projected onto a plane 108 perpendicular to the axis of motion 102, at least partially overlap with the roll suspension 132 when projected onto the same plane 108.

[0187] A first (radially inward) auxiliary frame 146a of the pair of auxiliary frames 146a, 146b forms a portion of the drive unit frame 130 and is attached (e.g., by an adhesive) to the remainder of the drive unit frame 130. A second (radially outward) auxiliary frame 146b of the pair of auxiliary frames 146a, 146b forms a first portion of the mounting frame 140 and is configured to be attached to the remainder of the mounting frame 140 by one or more snap-fit ​​connections 148.

[0188] The roll suspensions 142a, 142b are attached (eg, by adhesive) between a pair of auxiliary frames 146a, 146b.

[0189] The mounting frame suspensions 142a, 142b are configured to be positioned at equal distances from the center of gravity plane 108 in a direction parallel to the axis of motion 102 on opposite sides of the center of gravity plane when the diaphragm 110 is at rest.

[0190] The drive unit frame 130, mounting frame suspensions 142a, 142b, and auxiliary frames 146a, 146b may be pre-formed as a single unit that may be snap-fitted to the rest of the mounting frame 140. This may help to simplify assembly of the loudspeaker assembly 100.

[0191] like Figure 1 As shown, a portion 134 of the drive unit frame 130 extends between the mounting frame suspension 142 and the drive unit suspension 132. This portion 134 of the drive unit frame 130 is substantially continuous (e.g., closed) to prevent sound interference from the first radiating surface 112 and the second radiating surface 114 of the diaphragm (e.g., to inhibit sound generated by the first radiating surface 112 from reaching the second radiating surface 114 via the gap between the drive unit frame 130 and the mounting frame suspension 142).

[0192] A gap 150 is provided between the drive unit frame 130 and the mounting frame 140 to allow the drive unit frame 130 to move freely within the mounting frame 140, for example, to allow the drive unit 120 102 to move the diaphragm 110 along the axis of motion while suspending the drive unit frame 130 from the mounting frame 140 via the mounting frame suspension 142. However, the gap 150 is preferably minimized to maximize the drive unit frame size within the mounting frame 140 and, therefore, maximize the effective radiating surface area 154 of the first radiating surface 112 within the mounting frame 140. Thus, the gap 150 is preferably 3 mm or less, as measured in a plane perpendicular to the axis of motion at one or more locations around the perimeter of the drive unit frame 130 (and preferably for substantially the entire path extending around the drive unit frame). The gap 150 is preferably 1 mm or greater for substantially the entire path extending around the drive unit frame 130 at the perimeter of the drive unit frame 130 to reduce the risk of the drive unit frame 130 contacting the mounting frame 140 due to manufacturing tolerances.

[0193] The effective radiation surface area 154 of the first radiation surface 112 is preferably 60 cm 2 or larger.

[0194] Ideally, the shape of the diaphragm 110 is selected to closely match the shape of the space provided by the mounting frame 140. In this example, the diaphragm 110 has an oval or racetrack shape. Figure 1 The cross-sectional view through the diaphragm 110 to the right and left sides of the drive unit 120 is shown with different sizes, and Figure 2A Shown in.

[0195] However, the shape of the diaphragm may not completely correspond to the shape of the space provided by the mounting frame 140. As can be seen, the gap 150 between the drive unit frame 130 and the mounting frame 140 may have different sizes measured in a plane perpendicular to the axis of motion at different locations around the periphery of the drive unit frame 130.

[0196] Diaphragm 110 includes a pattern of corrugations 160 similar to that described in WO 2005 / 015950 A1. When viewed circumferentially, each corrugation has a depth that increases from the inner and outer peripheral edges of diaphragm 110 toward a base region 162 located between the outer and inner peripheral edges of diaphragm 110. Base region 162 is located approximately midway between the outer and inner peripheral edges of diaphragm 110. The maximum depth of each corrugation 160 is located at base region 162, and corrugations 160 are provided with surfaces 164 (which are part of second radiating surface 114) at base region 162, to which the outer edges of spiders 166 are attached.

[0197] A circular reinforcement element 168 comprising corrugations (similar to the circular reinforcement element described in WO 2008 / 135857 A1 ) is attached to the dampers 166 at the base region 162 , thereby reinforcing the diaphragm 110 at one or more base regions 162 of the diaphragm.

[0198] The damper 166 is secured at its inner edge (e.g., by adhesive) to the driver frame 130 and at its outer edge to the surface 164 of the corrugations 160 at the base region 162 of the diaphragm 110. For example, the reinforcing element 168 may be made of a material selected from paper, aluminum, titanium, polypropylene, polycarbonate, acrylonitrile butadiene styrene, or Kevlar. TM made of materials.

[0199] The mounting frame 140 is only partially shown in Figure 2 and is the support foam area of ​​the automotive headrest. The complete headrest is not shown in Figure 2, but it can be similar to the headrest shown in Figure 9 below.

[0200] like Figure 2C As shown, the drive unit 120 is an electromagnetic drive unit including a magnet unit 170 and a voice coil 122. The voice coil 122 is attached to the inner peripheral edge of the diaphragm 110 via a tubular member 124 of a voice coil coupler. Specifically, the voice coil 122 is wound around the tubular member 124 and is configured to be excited by passing an electric current through it via a wire 183.

[0201] The wires 183 lead to at least one electrical connector 185 for receiving a cable (not shown) to connect the voice coil 122 to an audio source (not shown) via the cable and wires 183. Although only one connector 185 is shown in the figure, there may actually be two connectors 185. Figure 1 , one or more connectors 185 are shown attached to an inward-facing surface of the drive unit frame 134 .

[0202] A dust cover 180 is attached to the tubular element 124 of the voice coil coupling.

[0203] The magnet unit 170 is located in front of the second radiating surface 114 of the diaphragm 110. The magnet unit 170 includes a permanent magnet 172, a U-shaped yoke 174 (preferably formed of steel), and a steel washer 175 (which includes an upper portion 175a and a lower portion 175b). Figure 1 As shown, the magnet unit 170 provides an air gap 128 in which the voice coil 122 is configured to be located when the diaphragm 110 is at rest. Specifically, the air gap 128 is located between the permanent magnet 172, the steel washer 175 and the U-shaped yoke 174.

[0204] The steel washer 175 includes a cutout 176 (see, for example, Figure 2C), which is located at a position along a direction parallel to the motion axis 102, which is adjacent to the voice coil 122 when the diaphragm 110 is at rest. A shorting ring 178 is positioned in the cutout 176. The shorting ring 178 may include, for example, copper.

[0205] In use, the voice coil 122 can be energized (by passing current through it) to generate a magnetic field that interacts with the magnetic field generated in the air gap 128 by the magnet unit 170 and causes the voice coil 122 (and therefore the diaphragm 110 ) to move relative to the magnet unit 170 .

[0206] Permanent magnet 172 and U-shaped yoke 174 are configured such that the magnetic flux density in air gap 128 reaches a first local maximum peak position parallel to axis of motion 102 and a second local maximum peak position parallel to axis of motion 102. The first peak position and the second peak position are spatially separated by a valley region parallel to axis of motion 102, in which the magnetic flux density is lower than the first and second local maxima. Voice coil 122 is configured to be positioned in the valley region when diaphragm 110 is at rest. The aforementioned shorting ring 178 can help achieve such a magnetic flux density. A similar example is provided in PCT / EP2020 / 064577.

[0207] In use, the drive unit 120 can be configured to move the diaphragm 110 at bass frequencies, for example, across a range of 40-100 Hz. The mounting frame suspensions 142a and 142b are configured to have a resonant frequency between 10 Hz and 30 Hz. A theoretical explanation of how at least one mounting frame suspension can be adjusted to achieve such a resonant frequency is described in further detail below.

[0208] Because the mounting frame suspensions 142a, 142b extend substantially continuously around the driver frame 130, they inhibit the sound generated by the first radiating surface 112 from reaching the second radiating surface 114 via the gap between the mounting frame 140 and the driver frame 130 formed by the mounting frame suspensions 142a, 142b. Consequently, the sound generated by the first radiating surface 112 and the anti-phase sound generated by the second radiating surface 114 are directed around the mounting frame (e.g., the headrest). Consequently, interference will still occur, albeit at a greater distance from the diaphragm (due to the increased path length provided by the headrest), as desired for a personal sound cocoon.

[0209] Furthermore, because the mounting frame suspensions 142 a , 142 b extend substantially continuously around the drive unit frame 130 , the mounting frame suspensions 142 a , 142 b can reduce lateral rocking of the diaphragm 110 / drive unit frame 130 in any direction not parallel to the motion axis 102 .

[0210] Furthermore, since the mounting frame suspensions 142 a , 142 b are formed in the gap between the drive unit frame and the mounting frame, the mounting frame suspensions may serve as barriers without increasing the height of the dipole speaker 100 .

[0211] Still further, by having the mounting frame suspensions 142a, 142b at least partially overlap the roll suspension 132 when projected onto the same plane 108, the effective radiating surface area 154 of the diaphragm 110 can be increased within a given space (e.g., within a mounting frame 140 for housing a speaker, which may be part of the base of a headrest in an automobile, for example).

[0212] The mounting frame suspensions 142a, 142b and auxiliary frames 146a, 146b may be referred to as a mounting frame arrangement.

[0213] The mounting frame arrangement may optionally be provided as a composite part for attaching the dipole loudspeaker 101 to (the remainder of the mounting frame) 140. The composite part may initially be formed as a separate component from (the remainder of) the drive unit frame 130 and / or (the remainder of) the mounting frame 140. Thus, the composite part may be attached to (the remainder of) the drive unit frame 130 and / or (the remainder of) the mounting frame 140. Such attachment may be via one or more snap connections or by any other connection means (e.g., by adhesive, glue beads, self-adhesive tape, and / or by friction fit).

[0214] Alternatively, one or more components of the mounting frame arrangement may be formed integrally with (the remainder of) the mounting frame and / or the drive unit frame.

[0215] Figures 3A to 3H Illustrated are cross sections of several examples of mounting frame suspension arrangements that may be used as (or in place of) Figure 1 The dipole loudspeaker 100 is arranged in a mounting frame with suspension members.

[0216] Figure 3A An exemplary mounting frame arrangement is shown that includes two mounting frame suspensions (optionally configured as composite parts). Each mounting frame suspension includes roll suspensions 144a, 144b, which are separated by a distance D by a pair of rigid auxiliary frames 146a, 146b. As described above, rigid auxiliary frame 146a is part of drive unit frame 130, and rigid auxiliary frame 146b is part of mounting frame 140. Distance D can be, for example, less than 30 mm, preferably less than 25 mm, and more preferably less than 20 mm. Distance D is preferably greater than 5 mm.

[0217] Separating the two roll suspensions 144a, 144b by a distance D (preferably between 5 mm and 20 mm inclusive) in the direction of the axis of motion (in this case using rigid auxiliary frames 146a, 146b) helps prevent the diaphragm 110 / drive unit frame 130 from rocking without having to increase the height of the dipole loudspeaker.

[0218] The pair of roll suspension members 144a, 144b may comprise rubber, pressed or non-pressed foam, or fabric, among others. The choice of material, as well as the length L, thickness T, distance D, and shape of the roll suspension members, may be varied to define the overall stiffness of the mounting frame suspension. The desired overall stiffness of the mounting frame suspension members 142a, 142b is discussed in further detail below.

[0219] exist Figure 3A In the example shown, the roll suspension members 144a, 144b are curved away from each other.

[0220] Figure 3B An exemplary mounting frame arrangement (optionally provided as a composite part) is shown, similar to Figure 3A The composite part is shown, except that the pair of roll suspension members 144a, 144b are curved toward each other.

[0221] In addition, if Figure 3B As shown, a pressure equalization vent 184 is formed in one of the auxiliary frames 146a. The pressure equalization vent 184 can help prevent pressure buildup in the space between the two roll suspensions 144a, 144b and the pair of auxiliary frames 146a, 146b.

[0222] Figure 3C and Figure 3D Other exemplary mounting frame arrangements (optionally provided as composite parts) are shown. Figure 3C and Figure 3D Instead of providing a roll suspension, the illustrated mounting frame suspensions each comprise a sheet of elastic material 182a, 182b held taut between a pair of auxiliary frames 146a, 146b. When mounted in a loudspeaker, the sheet / sheets of elastic material 182a, 182b may have little or no slack when held between the auxiliary frames 146a, 146b, such that the elastic material 182a, 182b is substantially unstretched when the diaphragm 110 is at rest. The sheet / sheets of elastic material may comprise a resilient foam or (silicone) rubber.

[0223] Figure 3C A composite part is shown comprising two sheets of elastic material 182a, 182b separated by a distance D by two auxiliary frames 146a, 146b (wherein the auxiliary frames 146 may be similar to those described above with reference to FIG. Figure 3Aauxiliary framework described).

[0224] exist Figure 3D In the example shown, the composite part includes a single piece of elastic material 182 .

[0225] exist Figure 3C and Figure 3D The overall stiffness of the mounting frame suspension(s) in the example shown is defined by the amount of elastic material 182(a / b) allowed to elastically elongate.

[0226] Figure 3E An exemplary mounting frame arrangement (optionally provided as a composite part) is similar to Figure 3A 146a, 146b overlap each other when projected onto a plane perpendicular to the axis of motion, such that when installed in the loudspeaker assembly, the overlapping portions of the subframes 146 serve to prevent the drive unit frame 130 from being ejected from the mounting frame 140 (e.g., in the event of a crash or other event involving sudden deceleration of the loudspeaker). Furthermore, one roll suspension 144b includes a pressure equalization vent 184 that can help prevent pressure buildup in the space between the two roll suspensions 144a, 144b and the pair of subframes 146a, 146b.

[0227] Figures 3F to 3H The exemplary mounting frame arrangements shown (optionally provided as composite parts) each include a block of elastic material 186 as a suspension of the mounting frame.

[0228] Figure 3F The elastic material block used as the mounting frame suspension comprises a non-pressed elastic foam. The stiffness of this mounting frame suspension is defined by the elastic elongation, free length L, and thickness T of the foam. In this example, the mounting frame suspension (e.g., elastic foam block 186) can be attached to the mounting frame and drive unit frame by one or more self-adhesive strips 188 to facilitate assembly of the drive unit frame within the mounting frame. The elastic material block 186 can be attached to the auxiliary frame 146b of the mounting frame 140.

[0229] Figure 3G The exemplary mounting frame suspension shown is similar to Figure 3F The mounting frame suspension shown includes, in addition to the elastic material block 186, a plurality of corrugations or cutouts 190 to help adjust the elastic material block to a desired stiffness. The elastic material block also includes one or more snap-fit ​​elements 192 (e.g., protrusions or recesses) for providing a snap-fit ​​connection with the drive unit frame 130 and / or the mounting frame 140 (in this case, providing a snap-fit ​​connection with the drive unit frame 130).

[0230] exist Figure 3HIn the exemplary mounting frame suspension shown, the block of resilient material 186 is hollow and is preferably made of rubber and includes a plurality of cavities and / or corrugations 194 to increase the stability of the mounting frame suspension.

[0231] Figure 4 A cross-sectional view of an exemplary dipole loudspeaker assembly 200 including a dipole loudspeaker 201 is shown. The dipole loudspeaker assembly 200 is similar to Figure 1 The dipole loudspeaker assembly 100 is shown.

[0232] Here, the drive unit frame 230 is suspended from the mounting frame 240 by two mounting frame suspensions 242a and 242b. The two mounting frame suspensions 242a and 242b are spaced apart in a direction parallel to the axis of motion 202. Each mounting frame suspension 242a and 242b is configured to be positioned equidistant from the center of gravity plane on opposite sides of the center of gravity plane in a direction parallel to the axis of motion 202 when the diaphragm 210 is at rest. Providing the two mounting frame suspensions 242a and 242b in this manner can help improve the stability of the dipole loudspeaker 200.

[0233] and Figure 1 The exemplary dipole loudspeaker shown is different in that Figure 4 In the installation frame suspension parts 242a, 242b and Figure 3F The mounting frame suspensions shown are similar. Specifically, each of the mounting frame suspensions 242a, 242b comprises a non-pressed resilient foam block that is directly attached to both the mounting frame 240 and the drive unit frame by adhesive (eg, by one or more self-adhesive strips 288).

[0234] Furthermore, the damper 266 is secured to the voice coil coupling's tubular element 224 (and therefore indirectly to the diaphragm 210) rather than being directly attached to the diaphragm 210. Specifically, the damper 266 is secured at its outer edge to the driver frame 230 and at its inner edge to the voice coil coupling's tubular element 224.

[0235] In this example, the illustrated portion of mounting frame 240 is a foam material, such as a resilient foam material.

[0236] Another difference between the dipole loudspeaker assembly 200 and the dipole loudspeaker assembly 100 is that the drive unit frame 230 includes one or more protruding flanges 296 , which may aid in manufacturing and, in particular, in adhering the one or more mounting frame suspensions 242a , 242b to the mounting frame 240 .

[0237] Figure 5 An exemplary dipole speaker assembly 300 is illustrated, comprising a dipole speaker 301. The dipole speaker assembly 300 is similar to the Figure 1 The dipole loudspeaker assembly 100 is shown, except that the driver suspension 332 does not extend completely continuously around the diaphragm 310. Instead, to maximize the effective radiating surface area of ​​the diaphragm 310 within the space provided by the mounting frame 340, the driver suspension 332 is interrupted at one or more locations around the outer edge (e.g., the perimeter) of the diaphragm 310. At any location around the perimeter of the diaphragm 310 where the driver suspension 332 is interrupted (e.g., at any location where the driver suspension 332 is not present), the diaphragm 310 may include an upright or downwardly facing edge 311. Figure 5 As shown, the upright edge 311 of the diaphragm extends in a direction generally parallel to the outside of the drive unit frame 330 (in a direction generally parallel to the motion axis 302). The gap between the upright edge 311 and the outside of the drive unit frame 330 is preferably minimized and, when measured in a plane perpendicular to the motion axis 302, can be 2 mm or less (more preferably 1.5 mm or less, more preferably 1 mm or less, more preferably 0.8 mm or less, and in some cases even 0.5 mm or less).

[0238] Providing the upstanding edge 311 of the diaphragm 310 at a location around the periphery of the diaphragm 310 where there is no driver suspension 332 (wherein the gap between the upstanding edge 311 and the driver frame 330 is narrow (preferably less than 1 mm)) helps ensure high friction for air movement between the diaphragm 310 and the driver frame 330, while still allowing the diaphragm 310 to move along the axis of motion relative to the driver frame 330 302. This can help reduce acoustic interference from the first and second radiating surfaces of the diaphragm (e.g., reducing the amount of sound generated by the first radiating surface that reaches the second radiating surface via the gap).

[0239] The mounting frame 340 of the dipole loudspeaker assembly 300 also includes one or more safety stops 341 (e.g., protrusions). The safety stops 341 protrude into the space provided by the mounting frame 340 and, together with the overlapping portions of the auxiliary frames 346a, 346b, are configured to prevent the driver frame 330, and therefore the driver 320, from passing through the diaphragm 310 and ejecting from the mounting frame 340, such as in the event of a crash or another event involving sudden deceleration of the loudspeaker 300 (e.g., where the loudspeaker 300 has moved in the direction of the primary radiation axis of the first radiating surface). Specifically, the safety stops 341 are configured to engage with the auxiliary frames 346b, which in turn are configured to engage with the overlapping portions of the auxiliary frames 346a, to prevent the driver frame 330, and therefore the driver 320, from passing through the diaphragm 310 and ejecting from the mounting frame 340, such as in the event of a crash or other event involving sudden deceleration of the loudspeaker 300. The one or more safety stops 341 are preferably rigid.

[0240] In this example, the loudspeaker includes a mounting frame arrangement (auxiliary frames 346a, 346b and mounting frame suspensions 342a, 342b) formed with Figure 3E Composite parts similar to the parts illustrated.

[0241] As can be seen, during manufacturing, the drive unit frame 330 (and the drive unit 320) can be inserted into the mounting frame 340 from the second (rear) side (e.g., in a direction parallel to the primary radiating axis of the first radiating surface). The drive unit frame 330 can be pushed into the space provided by the mounting frame 340 until the auxiliary frame 346 attached to the mounting frame suspension 342 engages (e.g., abuts) with the safety stop 341 of the mounting frame 340. Because the auxiliary frames 346 overlap each other, the pair of roll suspensions (i.e., the pair of mounting frame suspensions 342a, 342b) are not overly stressed or damaged during assembly. The auxiliary frame 346, and therefore the drive unit frame 330, is then locked in place by one or more snap connections (e.g., by snap elements 343) to form the loudspeaker assembly 300.

[0242] Figure 6 Illustrated is an exemplary dipole loudspeaker 400 comprising a dipole loudspeaker 401. Dipole loudspeaker 400 is similar in principle to dipole loudspeaker 100, except for a number of differences discussed herein.

[0243] Specifically, the diaphragm 410 of the dipole loudspeaker 401 is not a sheet-like diaphragm (e.g., paper), but rather a solid block of lightweight material, such as extruded or expanded foam of polypropylene (PP), polyurethane (PU), or polystyrene (PS). For example, the diaphragm 410 may have a thickness greater than 5 mm in a direction perpendicular to the axis of motion 402.

[0244] The U-shaped yoke 474 of the magnet unit 470 is a slotted yoke (eg, including a plurality of slots extending therethrough in a direction parallel to the motion axis 402 ).

[0245] In this example, the voice coil coupler includes a tubular member 424 and a plurality of ribs 425 extending radially outward from the tubular member 424 through slots in the slotted U-shaped yoke 474. The ribs 425 are plate-shaped and extend into the interior of the diaphragm 410. The ribs 425 are preferably made of a rigid, lightweight, non-conductive material (e.g., balsa wood). This provides reinforcement to the diaphragm 410.

[0246] Furthermore, in contrast to the dipole loudspeaker 101, the dipole loudspeaker 401 includes two drive unit suspensions 432a, 432b, and specifically two roll suspensions. A first roll suspension 432a is attached to the first radiating surface 412 of the diaphragm, and a second roll suspension 432b is attached to the second radiating surface 414 of the diaphragm 410. This can help stabilize the diaphragm 410.

[0247] In this example, one or more of the mounting frame suspensions 442a, 442b are interrupted to allow passage of a portion of the drive unit frame 430. Specifically, one or more small discontinuities exist in one of the pair of roll suspensions 442a to allow passage of a portion of the drive unit frame 430. However, these one or more discontinuities are small enough that the blocking effect of the mounting frame suspensions 442a, 442b is still achieved.

[0248] exist Figure 6 , the dashed line indicated as 498 represents the maximum extent of the diaphragm 410 and the drive unit suspension 432b in a direction toward the mounting frame suspension 442a. For performance reasons, it is important to ensure that the dipole loudspeaker assembly 400 is designed / constructed to avoid contact between the drive unit suspension 432b, the diaphragm 410, and the mounting frame suspension 442a.

[0249] In this example, a wire 482 for exciting the voice coil 422 extends over the first radiating surface 412 of the diaphragm 410 , over the driver suspension 432 a , and through the mounting frame 440 to a power source.

[0250] Figure 7 as well as Figure 8A and Figure 8B Shows something like Figure 6 A different view of an exemplary dipole loudspeaker assembly 500 including a dipole loudspeaker 501 is shown of the dipole loudspeaker assembly 400 .

[0251] Similar to the dipole loudspeaker 401, and as Figure 8A and Figure 8B As shown, a plurality of ribs 525 extend radially outward from the voice coil coupling tubular member 524 through the slots in the slotted U-shaped yoke. The ribs 525 are plate-shaped and extend to the interior of the diaphragm 510. Wires 582 extend over the diaphragm 510 and over the driver suspension 532a.

[0252] In contrast to the dipole loudspeaker 401, and as Figure 7 As shown, in the dipole loudspeaker 501, one or more portions of the peripheral edge of the diaphragm 510 extending between the first radiating surface 512 and the second radiating surface 514 of the diaphragm 510 are curved (see FIG. Figure 7 This can help maximize the effective radiating surface area of ​​the first radiating surface 512 of the diaphragm 510, especially when one (or both) of the roll suspensions 532a, 532b is interrupted (e.g., Figure 8A and Figure 8B ) when best shown in .

[0253] The diaphragm 510 is also shaped to avoid interference with the drive unit frame 530. Specifically, the cutout 519 of the diaphragm 510 helps to avoid interference with the drive unit frame 530 (see FIG. Figure 7 right-hand side of the diaphragm 510 shown).

[0254] like Figure 7 As shown, the mounting frame suspension 542 of the speaker assembly 500 is similar to Figure 3D The mounting frame suspension shown. Specifically, the mounting frame suspension 542 includes a sheet of elastic material 582, which may include a highly elastic and over-molded rubber, such as silicone rubber.

[0255] Figures 9A to 9C An exemplary dipole speaker assembly 600 is shown in which a speaker 601 is mounted in a seat headrest 900 (only the seat headrest is shown in these figures). In many respects, the components in speaker assembly 600 are similar to those in speaker assembly 100, with the components being named similarly. However, for the sake of completeness, any speaker disclosed herein (e.g., exemplary speakers 101, 201, 301, 401, 501) may be mounted in headrest 900 in place of speaker 601.

[0256] The headrest 900 includes a rigid frame 930 , rigid mounting pins 940 for attaching the headrest to the rest of the seat (not shown), support foam 932 (which may be acoustically opaque), and acoustically transparent foam 934 .

[0257] The support foam 932 forms a waveguide that at least partially (preferably completely) surrounds the diaphragm of the speaker 601 (in a position perpendicular to the axis of motion) and is configured to direct sound generated by the first radiating surface and / or the second radiating surface of the diaphragm out to the opposite side of the headrest 900.

[0258] The rigid frame 930 and rigid mounting pins 940 form part of the rigid seat frame of the chair.The mounting frame suspension of the speaker assembly 600 helps to suppress vibrations generated by the movement of the diaphragm 210 of the speaker 200 from being transmitted to the body of a user sitting in the chair.

[0259] In this example, the entire rigid seat frame can be considered the mounting frame for the speaker assembly 600, but any structure on which the drive unit frame of the speaker 601 is suspended can also be considered the mounting frame (for example, only the auxiliary frame 646b can be considered the mounting frame).

[0260] like Figure 9B and Figure 9C For example, a seat incorporating a headrest 900 (the rest of the seat is not shown) is constructed to position a user sitting in the seat so that at least one (and preferably each) ear of the user is located at a listening position 40 cm or less (more preferably 30 cm or less, more preferably 25 cm or less, more preferably 20 cm or less, more preferably 15 cm or less) from the first radiating surface of the speaker 601.

[0261] The headrest has a front surface 910 configured to face the head of a user seated in the seat and a rear surface configured to face away from the head of the user seated in the seat. The speaker 601 is mounted in the headrest 900 such that the first radiating surface faces the front surface 910 of the headrest 900. The auxiliary frame 646b of the speaker assembly 600 is configured to be attached to the rest of the mounting frame via one or more snap connections.

[0262] The dipole speaker 601 is installed in the headrest 900 so that the headrest 900 is configured to allow the sound generated by the first radiating surface of the diaphragm 100 to propagate through the front surface 910 of the headrest 900 (via the acoustically transparent foam 934), and to allow the sound generated by the second radiating surface of the diaphragm to propagate from the rear surface 920 of the headrest 900 (via the acoustically transparent foam 934). Specifically, as shown in FIG9 , the frame 930 facing the rear surface 920 of the headrest 900 can be sufficiently open (e.g., the frame 930 can define a plurality of apertures therein) to allow the sound generated by the second radiating surface of the diaphragm to propagate from the rear surface 920.

[0263] One or more additional speakers may also be mounted in the headrest 900. In this example, two directional mid-high frequency speakers 800 are mounted in the headrest 900.

[0264] Acoustically transparent fabric or perforated leather 945 may substantially cover the headrest 900 to allow sound produced by the speakers 100 to transmit therethrough.

[0265] Now refer to Figures 10A to 10H Consider the technical considerations of designing a loudspeaker (eg, dipole loudspeakers 101 , 201 , 301 , 401 , 501 , 601 ) for use in a loudspeaker assembly.

[0266] Figure 10A and Figure 10B Simplified cross-sectional and front views of the loudspeaker assembly 1000 are shown, respectively.

[0267] First, the available space inside the mounting frame 1040 (eg, in a headrest) for housing the loudspeaker 1001 including the diaphragm 1010 is evaluated.

[0268] The size and shape of the diaphragm is then determined by arranging the optimal shape and size of the diaphragm 1010 in the available space. The optimal shape may be limited by the manufacturability of diaphragms of different shapes or by obstacles such as other required structural elements in the headrest (e.g., Figure 10B Obstacles 1020 in the middle). Typically, circular, elliptical or racetrack shaped diaphragms can be used.

[0269] Next, one or more mounting frame suspensions 1042 are designed for attaching the drive unit frame of the loudspeaker 1001 to the mounting frame 1040. Specifically, such mounting frame suspensions 1042 are preferably designed so as not to significantly affect the radiation surface area of ​​the dipole loudspeaker nor the height of the dipole loudspeaker (by designing the mounting frame suspension / each mounting frame suspension so that the mounting frame suspension / each mounting frame suspension, when projected onto a plane perpendicular to the axis of motion, at least partially overlaps with one or more elements selected from the diaphragm and the at least one drive unit suspension when projected onto the same plane, and so that the at least one mounting frame suspension is formed in the gap 1100 between the drive unit frame and the mounting frame and extends substantially continuously around the drive unit frame).

[0270] Next, the acoustic seal of the one or more mounting frame suspensions 1042 is evaluated to ensure that sound radiated from the first radiating surface of the dipole loudspeaker is prevented from problematically interfering with anti-phase sound radiated from the second radiating surface via the gap 1100 .

[0271] Next, the stiffness of the one or more mounting frame suspensions 1042 is evaluated.

[0272] Figures 10C to 10E The total stiffness K of the mounting frame suspension 1042 is calculated as follows: S2and tuning frequency F S2 The model assumes that the suspension is a single mounting frame suspension comprising elastic rubber or foam. Finite element modeling can alternatively be used to calculate the total stiffness K of the mounting frame suspension 1042. S2 and tuning frequency F S2 .

[0273] based on Figures 10C to 10E The total stiffness K of the mounting frame suspension 1042 is S2 [N / m] and tuning frequency F S2 [Hz] is given (for evaluation or measurement purposes) where we consider Ma to be grounded:

[0274]

[0275]

[0276] in,

[0277] ●E=Young's modulus [N / m 2 ]

[0278] ●T=thickness of the mounting frame suspension [m]

[0279] W = width of the mounting frame suspension (e.g. between inner and outer edges) [m]

[0280] L = free or unsupported length of the mounting frame suspension (i.e. when no forces are applied to the mounting frame suspension) [m]

[0281] ●S=length of the part of the mounting frame that supports or fixes the suspension to the mounting frame [m]

[0282] Mms = moving mass of the loudspeaker, where moving mass of the loudspeaker = mass of the diaphragm + air load + voice coil + part of the driver suspension [kg]

[0283] ●M f = Mass of drive unit frame + drive unit + part of drive unit suspension [kg]

[0284] ●Ml=mass of the speaker=M f +Mms[kg]

[0285] Ma = mass of the headrest "applied" [kg]

[0286] ●R S2 = Mechanical loss of the mounting frame suspension [Ns / m]

[0287] BLi = Motor force [N]

[0288] kms = stiffness of the drive unit suspension [N / m]

[0289] Rms = Mechanical losses (friction) of the drive unit suspension [Ns / m]

[0290] Here, the "application" is the mass of the main body including the mounting frame. Typically, this would be the mass of the headrest and the mass of the backrest part of the seat frame of a car seat.

[0291] Used with models to produce Figure 10G and Figure 10H Example values ​​for these parameters for the graphs shown are as follows:

[0292] Rdc = 3.4 [ohms]

[0293] BLi = 2.5 [Tm]

[0294] Kms = 0.5 [N / mm]

[0295] Rms=1[Ns / m]

[0296] ●Mms=10[g]

[0297] Mf = 250 [g]

[0298] ●Ma=5[kg]

[0299] Ks2 = 1 [N / mm (result is Fs2 = 10 Hz)] or Ks2 = 4 [N / mm (result is Fs2 = 20 Hz)]

[0300] Rs2=1[Ns / m]

[0301] Figure 10F A vehicle seat is shown in which the axis extending through the backrest and the headrest forms an angle α [degrees] with the vertical.

[0302] Figure 10G Shows the static deflection Xstat of the mounting frame suspension t Plot of [m] versus the tuning frequency Fs2 [Hz] of the mounting frame suspension.

[0303] like Figure 10G As shown, at all values ​​of α, if the tuning frequency of the mounting frame suspension is below 10 Hz, the required Xstat size becomes too large to be accommodated by a practical loudspeaker.

[0304] at last, Figure 10H Shown are tuning frequencies F of 10 Hz and 20 Hz for a 2 Vrms input and mounting frame suspension. S2Plots of the force Ma acting on the application (e.g. mounting frame) and the force (Mms) acting on the moving mass of the loudspeaker versus frequency.

[0305] like Figure 10H As shown, at the tuning frequency F S2 = 10Hz, the force transmitted to the application is low and the diaphragm (Mms) has a smooth frequency response. S2 = 20 Hz, there is an increased force acting on the application, and this force occurs at a higher frequency, and the diaphragm (Mms) has a less smooth frequency response, although this less smooth frequency response is at F S2 = around 20 Hz, which causes few problems since this is below the operating audio range.

[0306] consider Figure 10G and Figure 10H , we can see that usually the lower tuning frequency F S2 It is better to reduce the amount of vibration transmitted to the user (via the application), but this comes at the expense of large static deflections, which become impractical below about 10 Hz. Therefore, the preferred tuning frequency F of the mounting frame suspension is S2 Between 10 and 30 Hz, more preferably between 10 and 20 Hz.

[0307] Figures 11A to 11G Another dipole loudspeaker assembly 1100 is shown for producing bass frequency sounds.

[0308] Figures 11A to 11G The dipole speaker assembly 1100 is provided in the form of a dipole speaker module that is configured to be mounted in a seat headrest. Figures 11A to 11G The dipole speaker assembly 1100 will be referred to as a dipole speaker module 1100 .

[0309] The dipole speaker module 1100 includes a dipole speaker 1101 and a mounting frame suspension 1142a, 1142b, which is similar to Figure 1 The dipole loudspeaker 101 and mounting frame suspensions 142a, 142b are shown. Like features are given like reference numerals and require no further description except for certain notable differences described below.

[0310] Figure 11A The front side of the dipole speaker module 1100 is shown, which is intended to face the head of a user sitting in a chair. Figure 11B The same front side of the dipole speaker module 1100 is shown, but with the first protective grille 141 a omitted.

[0311] Figure 11CThe back side of the dipole speaker module 1100 is shown, which is intended to face away from the head of a user sitting in a chair. Figure 11D The same back side of the dipole speaker module 1100 is shown, but with the second protective grille 141 b removed.

[0312] Figure 11E and Figure 11F A cross section of a dipole loudspeaker module 1100 is shown.

[0313] Figure 11G Shown is a dipole loudspeaker module 1100 mounted in the headrest of a seat (in this example a car seat). Here, only a portion of the headrest is shown, with only the support foam area 1132 and the open-cell foam area 1152 of the headrest being visible.

[0314] The mounting frame 1140 of the dipole speaker module 1100 is connected to the Figure 1 The mounting frame 140 differs in that it includes:

[0315] an attachment structure 1143 on the mounting frame 1140 , wherein the attachment structure is configured to attach the mounting frame 1140 to the rigid structure of the headrest, which in this example is a rigid frame embedded in a support foam area of ​​the seat headrest;

[0316] a first protective grid 1141a attached to the mounting frame 1140 and positioned in front of the first radiating surface 1112 of the diaphragm 1110;

[0317] A second protective grid 1141 b is attached to the mounting frame 1140 and positioned in front of the second radiating surface 1114 of the diaphragm 1110 .

[0318] exist Figures 11A to 11G In the example shown, the attachment structure 1143 has the form of an ear that protrudes radially outward from the dipole speaker module 1100. In this example, the ear includes a screw hole 1143a.

[0319] exist Figure 11G In the example of FIG. 1 , a dipole speaker module 1100 is mounted in a supporting foam region 1132 of a headrest (here, a car headrest), wherein an attachment structure 1143 is used to attach the dipole speaker module 1100 to the supporting foam region using screws 1143 b, which pass through screw holes 1143 a in the attachment structure 1143 and are then screwed into a rigid frame embedded in the supporting foam region 1132. When the dipole module 1100 is mounted in the supporting foam region 1132 via the screw holes 1143 a and the screws 1143 b, the supporting foam region can be optionally considered as part of the mounting frame of the dipole speaker module 1100.

[0320] like Figure 11A、 Figure 11C and Figure 11G For illustration, in this example, the first and second protective grilles 1141a, 1141b are acoustically transparent, but provide two functions:

[0321] ● They help protect the dipole loudspeaker 1101 during testing and operation, for example at the headrest manufacturer

[0322] • They provide a surface for supporting the open cell foam used to cover the dipole speaker module 1100 during installation in the headrest

[0323] exist Figure 11G In the example of FIG. 1 , the first protective grid 1141a is shaped to follow the contours of the surrounding support foam area 1132 of the headrest. The first protective grid 1141a and at least a portion of the surrounding support foam area 1132 are covered with open-cell foam to provide the desired headrest shape. The contours of the first protective grid 1141a and the surrounding support foam area 1132 are preferably shaped relative to each other so that they can be covered by a uniform thickness of open-cell foam 1152 (e.g., Figure 11G Here, using foam of uniform thickness helps to simplify the manufacturing process.

[0324] The second protective grid 1141b may also be shaped to follow the contours of the surrounding support foam area and may also be covered with open cell foam to provide the desired headrest shape, although this is not recommended in the future. Figure 11G Not shown.

[0325] The module 1100 has two electrical connectors 1185, wherein each electrical connector 1185 is used to receive a cable (not shown) for connecting the voice coil 122 to an audio source (not shown) via the cable (and wires 1183). Figure 1 11 is located on the exterior of the mounting frame 1140. The inventors have observed that positioning the electrical connector 1185 on the exterior of the mounting frame 1140 has the following advantages: any cables connected to the electrical connector 1185 will not compromise the movement of the loudspeaker suspended in the frame. Note that the wires 1183 extend well above the mounting frame suspension 1142b, all within the module 1100.

[0326] The features disclosed in the above description or the appended claims or the drawings (expressed in their specific form or in terms of a device for performing the disclosed function, or a method or process for obtaining the disclosed result) may be used, as appropriate, alone or in any combination of these features to realize the invention in its different forms.

[0327] Although the present invention has been described in conjunction with the above exemplary embodiments, many equivalent modifications and variations will be apparent to those skilled in the art when the present invention is given. Therefore, the above exemplary embodiments of the present invention are intended to be illustrative rather than restrictive. Various changes may be made to the described embodiments without departing from the spirit and scope of the present invention.

[0328] For the avoidance of any doubt, any theoretical explanations provided herein are provided to improve the reader's understanding. The inventors do not wish to be bound by any of these theoretical explanations.

[0329] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.

[0330] Throughout this specification, including the claims that follow, unless the context requires otherwise, the words "comprise" and "comprising" and variations such as "comprises" and "comprising" will be understood to imply the inclusion of stated integers or steps or groups of integers or steps but not the exclusion of any other integers or steps or groups of integers or steps.

[0331] It must be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from "about" one particular value and / or to "about" another particular value. When such a range is expressed, another embodiment includes from the from particular value and / or to the other particular value. Similarly, when values ​​are expressed as approximations by use of the antecedent "about," it should be understood that the particular value forms another embodiment. The term "about" in connection with a numerical value is optional and means, for example, + / - 10%.

[0332] References

[0333] In order to more fully describe and disclose the present invention and the prior art related to the present invention, a number of publications are cited above. The complete citations of these references are provided below. The entire contents of each of these references are incorporated herein.

[0334] WO2005 / 015950A1

[0335] WO2008 / 135857A1

[0336] WO2019 / 121266A1

[0337] WO2019 / 121072

[0338] PCT / EP2020 / 064577

[0339] “Dynamical Measurement of the Effective Radiating area SD”,KlippelGmbH(https: / / www.klippel.de / fileadmin / klippel / Files / Know_How / Application_Notes / AN_32_Effective_Radiation_Area.pdf)

Claims

1. A dipole loudspeaker assembly for producing bass frequency sounds, the dipole loudspeaker assembly comprising: A dipole loudspeaker comprising: a diaphragm having a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite surfaces of the diaphragm; a drive unit configured to move the diaphragm along a movement axis at bass frequencies so that the first radiating surface and the second radiating surface generate bass frequency sound, wherein the sound generated by the first radiating surface is in anti-phase with the sound generated by the second radiating surface; a drive unit frame, wherein the diaphragm is suspended from the drive unit frame via at least one drive unit suspension, wherein the drive unit frame is configured to, in use, allow sound generated by the first radiating surface to propagate out of a first side of the dipole loudspeaker and allow sound generated by the second radiating surface to propagate out of a second side of the dipole loudspeaker; and a mounting frame, wherein the drive unit frame is suspended from the mounting frame via one or more mounting frame suspensions; wherein the / each mounting frame suspension, when projected onto a plane perpendicular to the axis of motion, at least partially overlaps one or more elements selected from the group consisting of the diaphragm and the at least one drive unit suspension, when projected onto the same plane; Wherein, at least one mounting frame suspension is formed in a gap between the drive unit frame and the mounting frame and extends substantially continuously around the drive unit frame.

2. The dipole loudspeaker assembly according to claim 1, wherein At one or more locations at the periphery of the drive unit frame, a gap between the drive unit frame and the mounting frame measured in a plane perpendicular to the axis of motion is 5 mm or less.

3. The dipole loudspeaker assembly according to claim 1 or 2, wherein: The surface area of ​​the first radiation surface is 60 cm 2 or larger.

4. A dipole loudspeaker assembly according to any one of the preceding claims, wherein The membrane comprises one or more corrugations, and wherein the / each corrugation extends radially between an inner peripheral edge and an outer peripheral edge of the membrane when viewed in the circumferential direction.

5. A dipole loudspeaker assembly according to any one of the preceding claims, wherein The at least one mounting frame suspension is configured to have a resonant frequency between 10 Hz and 30 Hz.

6. A dipole loudspeaker assembly according to any preceding claim, wherein: The drive unit frame is suspended from the mounting frame via a single mounting frame suspension, wherein the single mounting frame suspension is configured to be positioned on a center of gravity plane when the diaphragm is at rest.

7. The dipole loudspeaker assembly according to any one of claims 1 to 5, wherein: The drive unit frame is suspended from the mounting frame via two mounting frame suspensions, wherein the two mounting frame suspensions are spaced apart in a direction parallel to the motion axis.

8. The dipole loudspeaker assembly according to claim 7, wherein: The mounting frame suspensions are configured to be positioned on opposite sides of a center of gravity plane when the diaphragm is at rest and to be equidistant from the center of gravity plane in a direction parallel to the axis of motion.

9. The dipole loudspeaker assembly according to claim 7 or 8, wherein: Each mounting frame suspension is a roll suspension, and wherein the two roll suspensions are separated in a direction parallel to the axis of motion by a portion of the mounting frame and / or a portion of the drive unit frame.

10. The dipole loudspeaker assembly according to any one of claims 1 to 8, wherein: One or more mounting frame suspensions include: a sheet of resilient material held taut between the mounting frame and the drive unit frame; and / or Block of elastic material.

11. A dipole loudspeaker assembly according to any preceding claim, wherein The dipole speaker assembly is a dipole speaker module configured to be mounted in a seat headrest, wherein the dipole speaker module comprises: One or more attachment structures on the mounting frame, wherein the attachment structures are configured to attach the mounting frame to a seat headrest to thereby mount the dipole speaker module in the seat headrest.

12. The dipole loudspeaker assembly of claim 11, wherein: The dipole speaker module comprises: a first protective grid positioned in front of said first radiating face of said diaphragm; and / or A second protective grid is positioned in front of the second radiant face of the diaphragm.

13. The dipole loudspeaker assembly of claim 12, wherein: When the dipole loudspeaker module is mounted in the headrest, the / each protective grille is shaped to follow the contour of the surrounding area of ​​the headrest.

14. The dipole loudspeaker assembly of claim 13, wherein: The dipole loudspeaker module is mounted in the seat headrest and wherein, for the / each protective grille, the protective grille and the surrounding area of ​​the headrest are covered by open-cell foam of uniform thickness.

15. A dipole loudspeaker assembly according to any preceding claim, wherein The drive unit includes a magnet unit and a voice coil attached to the diaphragm via a voice coil coupler; The magnet unit includes a permanent magnet, a yoke and a steel washer; The magnet unit is configured to provide a magnetic field in an air gap, the air gap being provided between the permanent magnet and the yoke, the permanent magnet being located radially inward of the air gap relative to a direction parallel to the motion axis, and the yoke being located radially outward of the air gap relative to a direction parallel to the motion axis; the voice coil being configured to be located in the air gap when the diaphragm is at rest; The voice coil coupler includes a rib extending radially outward from the voice coil coupler through a slot in the yoke; and The rib of the voice coil coupler extends to the interior of the diaphragm.

16. The dipole loudspeaker assembly of claim 15, wherein: The steel washer includes a cutout at a location along a direction parallel to the axis of motion, the location being adjacent to the voice coil when the diaphragm is at rest, and wherein the cutout accommodates a shorting ring.

17. A seat assembly comprising: a seat for seating a user; as well as A dipole loudspeaker assembly according to any preceding claim, wherein the dipole loudspeaker is mounted in a headrest of the seat.

18. The seat assembly of claim 17, wherein: The headrest also includes one or more directional mid- and high-frequency speakers.

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