Bass speaker system
By adopting a multi-diaphragm and driving unit design in the woofer system, combined with a new suspension method of surround and bounce waves, the limitations of displacement and linear response in traditional woofers are solved, achieving more efficient sound quality improvement.
Patent Information
- Application Number
- CN202380055470.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-09-05
- Filing Date
- 2023-08-22
- Publication Date
- 2025-03-11
AI Technical Summary
In traditional woofers, due to the design limitations of the mechanical suspension device, the outer diameter of the elastic wave is limited by the frame, and large displacement and linear response cannot be achieved, which in turn affects the quality of the sound.
A new woofer system is adopted, by setting multiple diaphragms and driving units in the housing to form multiple moving components, and using surround members and elastic waves to hang from the housing, the design of larger elastic wave outer diameter and surround members is achieved, breaking the limitations of traditional manufacturing processes.
A linear response to large displacements is achieved, and the sound quality and performance of the woofer is improved, especially in the multi-mobile component configuration, which can more effectively eliminate the nonlinear impact of mechanical suspension.
Smart Images
Figure CN119605190A_ABST
Abstract
Description
[0001] This application claims priority to GB2212935.7 filed on September 5, 2022. Technical Field
[0002] The present invention relates to a woofer loudspeaker system. Background Art
[0003] In some conventional woofers, the moving assembly is suspended in a frame by a mechanical suspension device including a surround and a spider. In operation, the moving assembly is displaced along a moving axis to generate sound, which causes the surround and spider to deform.
[0004] Careful design of the surround, and in particular the spider, may be required to avoid sound distortion due to deformation of the surround and spider. It does not take much effort to design a conventional surround to provide a suitable linear response within the operating range of the woofer, where the mechanical dimensions of the surround can be related to the maximum displacement of the moving assembly. In contrast, the design of a suitable spider may require dedicated engineering efforts to achieve the desired linearity. Some conventional spiders have a wave-shaped body made of canvas-woven cloth, which is impregnated in a thermosetting resin and baked into the final shape. Parameters related to the stiffness of the spider and its response to deformation can include the number of waves of the wave-shaped body, the ratio of height to spacing, details of the cloth and weave type, the type of resin, and the resin density. For a given displacement, each of these parameters can have a significant effect on the stiffness of the spider. Even when these parameters have been optimally selected, the maximum achievable displacement is determined by the outer diameter of the spider, which the inventors have observed is limited by the frame of the woofer. Beyond a certain displacement, the stiffness curve of the spider may become very progressive, resulting in a nonlinear input-output relationship, whereby an increase in voltage does not translate linearly into a corresponding increase in displacement.
[0005] The present invention has been designed based on the above considerations. Summary of the invention
[0006] Known loudspeaker assemblies conventionally comprise a housing in which a loudspeaker is mounted. Due to conventional manufacturing processes, such as deep drawing and stamping or injection molding of polymers, the loudspeaker conventionally comprises a loudspeaker frame of (truncated) cone shape without undercuts, so that the loudspeaker frame can be effectively formed by one or several tools acting strictly axially with respect to the final main radiation axis of the loudspeaker. The resulting conical shape of the loudspeaker frame means that the outer diameter of the surround (mounted at the wide end of the conical shape) must be larger than the outer diameter of the spider (mounted towards the narrow end of the conical shape).
[0007] A bass speaker system is described herein that may be viewed as departing from these conventional manufacturing processes and breaking with the recognized design limitations. More particularly, the inventors have recognized that the outlined conventional speaker configuration of a moving assembly within a conical frame within an enclosure (or "box") may be replaced by an alternative configuration in which the frame and enclosure need not be separate structures, thereby addressing the recognized design limitations and resulting performance limitations.
[0008] Especially where multiple moving components are arranged together, such as in a force-canceling configuration, these components can be suspended within the same structure that serves as both the frame and the enclosure. In contrast, conventional speaker assemblies would rely on a separate frame for each speaker and an entire enclosure in which the individual speakers are mounted.
[0009] Due to the alternative configuration described herein, whereby the frame and housing need not be separate structures, certain structural limitations particularly affecting spider design may be addressed, as placement of the spider may not be limited by the available space in the conical speaker frame (as is the case in conventional speakers).
[0010] According to a first aspect of the present invention, a bass speaker system is provided, comprising: a shell; a first diaphragm and a second diaphragm; a first drive unit and a second drive unit, each drive unit comprising a fixed part and a translatable part attached to the shell; wherein the translatable part of the first drive unit is attached to the first diaphragm to form a first movable component suspended from the shell by a first surround and a first elastic wave, and the translatable part of the second drive unit is attached to the second diaphragm to form a second movable component suspended from the shell by a second surround and a second elastic wave; wherein the speaker is operable to excite the first drive unit and the second drive unit so that the first movable component and the second movable component move in opposite directions along a moving axis to generate sound; wherein the first surround comprises an external protrusion attached to the shell, an internal protrusion attached to the first diaphragm, and an external protrusion. and a surround body between the inner protrusion; wherein the second surround includes an outer protrusion attached to the shell, an inner protrusion attached to the second diaphragm, and a surround body between the outer protrusion and the inner protrusion; wherein the first elastic wave includes an outer protrusion attached to the shell, an inner protrusion attached to the first moving component, and a elastic wave body between the outer protrusion and the inner protrusion; wherein the second elastic wave includes an outer protrusion attached to the shell, an inner protrusion attached to the second moving component, and a elastic wave body between the outer protrusion and the inner protrusion; wherein the width of the elastic wave body of the first elastic wave measured in a measuring direction perpendicular to the moving axis is greater than the width of the surround body of the first surround in the said measuring direction; and wherein the width of the elastic wave body of the second elastic wave measured in the said measuring direction is greater than the width of the surround body of the second surround in the said measuring direction.
[0011] As outlined above in the background section, in a conventional woofer frame, having a spring that is wider than the surround may not be feasible due to accepted manufacturing practices and additional constraints. In contrast, the woofer system according to the first aspect does not adhere to these practices, but instead provides a housing that accommodates a first diaphragm and a first drive unit and a second diaphragm and a second drive unit without the need for a conventional frame therefor. This enables a wider spring (body) to be accommodated around the moving assembly and that extends beyond the surround. Therefore, a linear response to displacement can be achieved for displacements that are larger than what is possible with a conventional woofer, as the width of the suspension of a conventional woofer would be limited by the tapered shape of the individual speaker frames.
[0012] Note that the term "width" can be used to indicate the maximum extent of a structure (e.g., a waveguide / surround body) in a specified direction, i.e., the longest measurable extent of the structure in a specified direction, and can therefore be considered to follow the natural understanding of the term, as opposed to any arbitrary measurement in said direction.
[0013] In some examples, the width of the spring body of the first spring measured in any measurement direction perpendicular to the axis of movement can be greater than the width of the surround body of the first surround in the measurement direction (i.e., the width of the spring body of the first spring can be greater than the width of the surround body of the first surround in all possible measurement directions perpendicular to the axis of movement). However, this is not a requirement of the present invention, as examples can be envisioned in which the width of the spring body of the first spring is greater than the width of the surround body of the first surround in only one or more measurement directions (see, for example, the elliptical / racetrack deformation discussed in the detailed description below).
[0014] Where optional features are described below with respect to the first diaphragm and / or the first drive unit and / or the first surround and / or the first spring wave, it should be understood that such optional features may also or alternatively be applicable to the second diaphragm and / or the second drive unit and / or the second surround and / or the second spring wave.
[0015] The woofer speaker system as described above may be configured to produce sounds having frequencies in a bass frequency range. The bass frequency range may include 60 Hz-80 Hz, where "Hz" represents the physical unit "Hertz". More preferably, the bass frequency range may include 40 Hz-100 Hz. By way of example, the bass frequency range may be 20 Hz-100 Hz. The woofer speaker system may be provided as a subwoofer speaker system, which is configured to produce sounds only within a bass frequency range (e.g., 250 Hz or lower).
[0016] The housing may define an internal volume in the range of 0.25 liters to 5 liters, in which the speaker is mounted. In some examples, the internal volume may be up to 1.5 liters. Such a volume is typical for a bass speaker system.
[0017] The term "tab" may be considered to refer to a structural feature of a corresponding surround or spring wave by means of which the corresponding surround or spring wave is attached to another structure. Traditionally, the structural feature may have the shape of a tab, such as a flat portion, but other shapes are possible and may depend on the means by which the tab is attached to the other structure. In some examples, the tab may correspond to an edge of a surround or spring wave or along a line of the surround or spring wave.
[0018] The first drive unit and the second drive unit may be configured to be excited by the same signal. By utilizing the same signal, a complete cancellation of the forces resulting from displacing the first translatable part and the second translatable part may be achieved.
[0019] The first surround may be attached directly or indirectly to the first membrane.
[0020] The first damper (which may be referred to as a "centering spider") may be attached directly or indirectly to the moving assembly.
[0021] The measurement direction may correspond to the direction in which the width of the first spring body is shortest. In some examples, the first spring body may be non-circular, such as a racetrack shape. By arranging the shortest width of the first spring body to exceed the corresponding width of the surrounding body, a larger displacement may be achieved and the linear response to the displacement may be improved.
[0022] The outer tab of the first surround may be attached to the shell at a first surround landing surface on the shell.The outer tab of the first damper may be attached to the shell at a first damper landing surface on the shell.
[0023] The center of mass of the translatable part of the first drive unit may have a position along the axis of movement between the first surround landing surface and the first spider landing surface.
[0024] By suspending the moving assembly from the housing so that the center of mass of the translatable part of the first drive unit is located between the first surround landing surface and the first spider landing surface, the swaying of the moving assembly can be suppressed. More specifically, the swaying mode of the woofer system may be pushed outside the operating frequency range of the woofer system.
[0025] The mass of the translatable part of the first drive unit may correspond to the mass of the voice coil winding of the voice coil, or may alternatively correspond to the total mass of the permanent magnet and the flux guiding element. As described in further detail below, the translatable part of the first drive unit may include a voice coil or alternatively include a permanent magnet and a flux guiding element.
[0026] The woofer system may be operable to move the first moving component from a stationary position to a maximum displacement position. Moving the first moving component from the stationary position to the maximum displacement position may cause a deflection (i.e., deformation due to a load) of the first spring wave. The maximum spring wave deflection angle may be defined as the angle formed between: a first line extending between the innermost position on the outer tab of the first spring wave and the outermost position on the inner tab of the first spring wave when the first moving component is stationary; and a second line extending between the same innermost position on the outer tab of the first spring wave and the same outermost position on the inner tab of the first spring wave when the first moving component is in its maximum displacement position. The innermost position on the outer tab of the first spring wave and the outermost position on the inner tab of the first spring wave may be on the same side of the moving axis. The first line and the second line may extend in a plane containing the moving axis. For example, in order to maintain the linear performance of the spring wave, the maximum spring wave deflection angle may be 25 degrees or less.
[0027] The first driving unit may include a voice coil, a permanent magnet and a plurality of flux guiding elements.
[0028] Preferably, the fixed part of the first drive unit may comprise a permanent magnet and a plurality of flux guiding elements, wherein the translatable part of the first drive unit comprises a voice coil. The fixed part of the first drive unit may also comprise a voice coil, wherein the translatable part of the first drive unit comprises a permanent magnet and a plurality of flux guiding elements.
[0029] The total mass of the flux guiding element may be in the range of 0.8 to 1.2 times the mass of the permanent magnet.
[0030] The woofer system according to the first aspect enables the use of large drive units, and in particular large fixed parts. Thus, instead of having to rely on small high performance magnets, such as neodymium, relatively weak, large, but much more cost-effective permanent magnets may be used. Being relatively weak, the permanent magnets may make up a larger proportion of the fixed parts, since smaller flux guiding elements may be needed to accommodate the flux generated by the permanent magnets.
[0031] The first drive unit may include a ferrite magnet. Preferably, the permanent magnet may be a ferrite magnet. The density of ferrite is about 5 g / cm smaller than that of steel. 3 (grams divided by cubic centimeters), as may be typically used for flux guiding elements. Thus, using more ferrite and less steel may provide a surprisingly lightweight drive unit.
[0032] The permanent magnet of the first drive unit may have a mass in the range of 0.8 to 1.2 times the mass of the voice coil of the first drive unit, preferably wherein the permanent magnet is a ferrite magnet.
[0033] The permanent magnet of the first drive unit may have a mass smaller than the mass of the voice coil of the first drive unit, preferably wherein the permanent magnet is a neodymium magnet. That is, the permanent magnet of the first drive unit may have a first mass, the voice coil of the first drive unit may have a second mass, and the first mass may be smaller than the second mass. The first mass may be at least 2 times smaller than the second mass, or even at least 2.5 times, for example 2.8 times.
[0034] In conventional speakers, the mass of the permanent magnet is typically large compared to the mass of the voice coil. However, the wider spider of the present invention allows for a relatively heavy, and therefore large / dense, voice coil. This large / dense voice coil can be combined with a smaller and / or lighter permanent magnet (e.g., a ferrite magnet as described above), where the additional weight in the voice coil compensates for the weaker permanent magnet. Thus, the combination of a smaller permanent magnet and a larger / denser voice coil can help achieve desired performance parameters while reducing the weight of the speaker and the weight of the permanent magnet. Given the rising price of rare earth magnets, this can provide a more cost-effective configuration.
[0035] The housing may include a first housing portion, a second housing portion and a third housing portion. The third housing portion may be between the first housing portion and the second housing portion.
[0036] The first surround may be attached to the first housing portion. The first damper may be attached to the first housing portion or the third housing portion. The fixing part of the first drive unit may be attached to the third housing portion.
[0037] The second surround may be attached to the second housing portion. The second damper may be attached to the second housing portion or the third housing portion. The fixing part of the second drive unit may be attached to the third housing portion.
[0038] By providing three housing parts, assembly of the woofer system may be improved.
[0039] The first shell portion and the third shell portion may be joined together at a location outward from the outer tab of the first damper.
[0040] The second shell portion and the third shell portion may be joined together at a location outward from the outer tab of the second damper.
[0041] By joining the first / second housing portion to the third housing portion at a location outwardly from the outer tabs of the respective spiders, assembly of the woofer system may be improved.
[0042] The fixing part of the first drive unit may include a first U-shaped yoke. The fixing part of the second drive unit may include a second U-shaped yoke. Each U-shaped yoke may include a base and a wall extending from the base. The base of the first U-shaped yoke and the base of the second U-shaped yoke may be formed integrally.
[0043] By providing a combined yoke, which may be referred to as an "H-yoke", comprising a first U-shaped yoke and a second U-shaped yoke, the assembly and performance of a woofer system may be improved.
[0044] The translatable part of the first drive unit may include a voice coil. The first moving assembly may include a first sleeve extending along the axis of movement and around the voice coil and at least a portion of the fixed part of the first drive unit. The inner tab of the first spider is attached to the sleeve of the first moving assembly.
[0045] The first sleeve may provide an improved structure for attaching the first spider to the first moving assembly because the first sleeve extends around the first voice coil and a portion of the fixed part of the first drive unit. Therefore, the positioning of the first spider may be improved and swaying may be suppressed.
[0046] The first sleeve may define a plurality of first ventilation apertures therethrough to enable airflow through the first sleeve in a direction generally perpendicular to the axis of movement.
[0047] The voice coil former of the translatable part of the first drive unit may define a plurality of second vent holes therethrough to enable airflow through the voice coil former in a direction generally perpendicular to the axis of movement.
[0048] By providing the first and / or the plurality of second ventilation holes, internal blowing noise of air rushing through the first drive unit may be reduced.
[0049] The translatable part of the first drive unit may comprise a flux guiding element, such as a U-shaped yoke, and may comprise a permanent magnet. In contrast, the fixed part of the first drive unit may comprise a voice coil.
[0050] The flux guiding element may serve as the first diaphragm and the inner tabs of the first damper may be attached to the flux guiding element.
[0051] By providing the flux guiding element and the permanent magnet as translatable parts, the construction of the loudspeaker may be improved. Such improvement may involve extension of the leads or attachment of the first spider to the first moving component (eg by direct attachment to the flux guiding element).
[0052] The first damper may be arranged to divide the internal volume of the housing into a first volume at one side of the first damper and a second volume at the other side of the first damper. The first damper may form a plurality of ventilation holes therethrough to enable airflow to pass through the first damper. By providing ventilation holes passing through the first damper, internal blowing noise of air rushing through the first drive unit may be reduced.
[0053] A second aspect of the invention may provide a vehicle comprising a woofer system according to the first aspect. More particularly, the woofer system may be arranged in a footwell or under a seat of the vehicle, or indeed in any other location suitable for packaging the woofer system in the vehicle.
[0054] The present invention includes any combination of the described aspects and preferred features unless such a combination is expressly impermissible or explicitly avoided. BRIEF DESCRIPTION OF THE DRAWINGS
[0055] Embodiments and experiments illustrating the principles of the present invention will now be discussed with reference to the accompanying drawings, in which:
[0056] Figure 1 is a cross-sectional view of a loudspeaker assembly implementing known principles.
[0057] Figure 2 is a cross-sectional view of an exemplary loudspeaker.
[0058] Figure 3 It is a static configuration Figure 2 A cross-sectional view of a portion of a loudspeaker.
[0059] Figure 4 It is a displacement configuration Figure 2 A cross-sectional view of a portion of a loudspeaker.
[0060] Figure 5 is a cross-sectional view of another exemplary loudspeaker.
[0061] Figure 6 is a cross-sectional view of yet another exemplary loudspeaker.
[0062] Figure 7 is a cross-sectional view of yet another exemplary loudspeaker.
[0063] Figure 8 is a cross-sectional view of yet another exemplary loudspeaker.
[0064] Fig. 9 Yes Figure 2 Schematic diagram of a vehicle with speakers. DETAILED DESCRIPTION
[0065] Aspects and embodiments of the present invention will now be discussed with reference to the accompanying drawings. Further aspects and embodiments will be clear to those skilled in the art. All documents mentioned herein are incorporated herein by reference.
[0066] Figure 11 is a cross-sectional view of a loudspeaker assembly 1000 implementing known principles. Loudspeaker assembly 1000 includes a pair of woofers 1002 mounted in a box 1003. Each woofer 1002 includes a mobile assembly 1004 suspended in a frame 1005. Each mobile assembly is suspended in a corresponding frame 1005 by means of a surround 1006 and a spider 1007.
[0067] The frame 1005 has a generally conical shape to which the surround 1006 and the spring 1007 are attached and which, in turn, limits the size of the surround 1006 and the spring 1007. Figure 1 As can be seen in FIG. 1 , the surround 1006 is wider than the spring wave 1007 .
[0068] Each loudspeaker 1002 includes a drive unit 1008. The drive unit 1008 includes a ferrite ring magnet 1009, a T-yoke 1010 and a washer 1011, which in combination generate a static magnetic field for interacting with an excitation voice coil 1012 on a voice coil former 1013. The diameter of the voice coil former 1013 is the same as the inner diameter 1007 of the spider 1007. This arrangement, particularly for heavy voice coils 1012 and / or shallow loudspeakers, may increase the risk of rocking and rubbing of the voice coil 1012 relative to the static parts of the drive unit 1008.
[0069] Effective low frequency sound reproduction from a small closed box 1003 requires the moving mass of a relatively large speaker 1002. The force generated by the drive unit 1008 (or "motor system") moving this mass also generates an equal and opposite reaction force on the frame 1005. This causes vibrations of the box body. To counteract these forces on the box body, a motor such as Figure 1 Two speakers 1002 are shown mounted on opposite sides of a box 1003 .
[0070] The woofer 1002 can typically be manufactured separately and then installed in the box 1003. The box 1003 can be made of a polymer (such as PP or PC) by means of injection molding and can be preassembled from two half shells. Larger boxes are typically made of wood or engineered wood products (such as MDF or composite materials (Multiplex). In any case, their manufacture is completely independent of the loudspeaker 1002. The loudspeaker frame 1005 is traditionally made of metal either by means of deep drawing and stamping, or of a polymer by means of injection molding. In any case, it is preferred that there be no undercuts in the design, which means that it can be effectively formed by one or several tools that act strictly axially relative to the final main radiation axis 1019 of the loudspeaker 1002. This requirement results in the outer diameter of the surround always being larger than the outer diameter of the spider 1007. Making the loudspeaker 1002 follow the traditional large cone shape, the smaller spider and even the smaller magnet system allow for front installation in a preassembled box.
[0071] The size of the loudspeaker diaphragm 1020 relative to the size of the box has an effect on the resonant frequency in the box at a given moving mass. The larger the diaphragm 1020, the higher the resonant frequency in the box, because the enclosed air acts on the diaphragm 1020 and therefore provides additional stiffness in addition to the mechanical stiffness of the suspension elements 1006, 1007. Although this stiffness can be very high for a small box, it is linear with respect to the cone displacement, but not strictly constant. However, the mechanical stiffness of the loudspeaker 1002 is not constant, and engineering effort must be spent to maintain its linearity within the desired range. It does not take much effort to design a conventional rubber half-roll surround 1006 to be linear within the operating range of the loudspeaker 1002. The mechanical size is directly related to the maximum displacement. In contrast, a conventional spider 1007 is made of canvas-woven cloth that is immersed in a thermosetting resin and baked into its final shape, and may require dedicated engineering efforts to achieve the desired linearity. The number of waves, the ratio of height to spacing, the type of cloth and weave, the type of resin, and the resin density can all have a significant effect on the stiffness and displacement behavior of the spider 1007. For a given inner diameter of the spider 1007, the outer diameter defines the linear displacement that can be achieved, even when all other parameters are optimally selected. Beyond a certain displacement, the stiffness curve of the spider 1007 becomes very asymptotic, resulting in a nonlinear output-to-input relationship for the speaker 1002, since increasing voltage does not translate linearly into increasing displacement.
[0072] Another factor that can affect the space available for the spider 1007 is the selection and placement of the magnets 1009. Figure 1In known examples of the invention, the magnet 1009 is positioned radially outside of the voice coil 1012. Alternative arrangements with the magnet inside the voice coil 1012 may be less common and are primarily seen with neodymium magnets. The reason ferrite magnets inside the voice coil 1012 are rare is that their magnetic strength is weak compared to neodymium magnets and for a given voice coil size the magnetic field strength in the air gap may be too small for many applications. The inventors have envisioned that a possible solution to this may be to increase the diameter of the voice coil 1012, but this would necessarily increase the inner diameter of the spider 1007 and therefore may make it more difficult to achieve high linearity because the outer diameter of the spider 1007 is limited by the size of the cone and associated surround 1006 due to the standard manufacturing process of the frame 1005.
[0073] Therefore, for low frequency reproduction from a loudspeaker with a low intra-box resonant frequency from a small box 1003, it is desirable to have a smaller diaphragm with suspension from the surround and a spider that allows large and linear displacement.
[0074] Figure 2 , Figure 3 and Figure 4 An exemplary subwoofer system 10 is illustrated. Figure 2 is a cross-sectional view of the woofer system 10 . Figure 2 and Figure 3 is a cross-sectional view of a portion of woofer system 10 illustrating a rest position and a maximum displacement position. Figure 3 and Figure 4 Only shown Figure 2 A portion of the speaker system 10 is shown to help more clearly see its components.
[0075] The woofer system 10 includes a housing 100, first and second diaphragms 210 and 220, and first and second drive units 310 and 320. Each drive unit 310, 320 includes a fixed part 311, 321 attached to the housing 100 and a translatable part 312, 322.
[0076] The fixed part 311, 321 of each drive unit 310, 320 comprises a permanent magnet 313, 323 and a plurality of flux guiding elements 314, 315, 324, 325. The plurality of flux guiding elements comprises washers 314, 324 and yokes 315, 325 arranged as U-shaped yokes. The permanent magnet 313, 323 generates a static magnetic field between the washers 314, 324 and the U-shaped yokes 315, 325, which penetrates the translatable parts 312, 322 of the drive units 310, 320.
[0077] The total mass of the plurality of flux guiding elements 314, 315 of the first drive unit 310 may be in the range of 0.8 to 1.2 times the mass of the permanent magnet 313 of the first drive unit 310. Similarly, the total mass of the plurality of flux guiding elements 324, 325 of the second drive unit 310 may be in the range of 0.8 to 1.2 times the mass of the permanent magnet 323 of the second drive unit 320.
[0078] The translatable part 312 of the first drive unit 310 is attached to the first diaphragm 210 to form a first moving assembly 410. The translatable part 322 of the second drive unit 320 is attached to the second diaphragm 220 to form a second moving assembly 420. The speaker system 10 is operable to excite the first drive unit 310 and the second drive unit 320 to move the first moving assembly 410 and the second moving assembly 420 in opposite directions along the moving axis 12 to generate sound. More specifically, each diaphragm 210, 220 has a first sound radiating surface 211, 221 and a second sound radiating surface 212, 222. The first sound radiating surface 211, 221 faces away from the housing 100 and is used to generate sound.
[0079] The first moving assembly 410 is suspended from the housing 100 by the first surround 510 and the first spring 610. The first surround 510 includes an outer tab 512 attached to the housing 100, an inner tab 514 attached to the first diaphragm 210, and a surround body 516 between the outer tab 512 and the inner tab 514. The first spring 610 includes an outer tab 612 attached to the housing 100, an inner tab 614 attached to the first moving assembly 410, and a spring body 616 between the outer tab 612 and the inner tab 614.
[0080] Likewise, the second moving assembly 420 is suspended from the housing 100 by the second surround 520 and the second spring 620. The second surround 520 includes an outer protrusion 522 attached to the housing 100, an inner protrusion 524 attached to the second diaphragm 210, and a surround body 526 between the outer protrusion 522 and the inner protrusion 524. The second spring 620 includes an outer protrusion 622 attached to the housing 100, an inner protrusion 624 attached to the second moving assembly 420, and a spring body 626 between the outer protrusion 622 and the inner protrusion 624.
[0081] The width of the elastic wave body 616 of the first elastic wave 610 measured in the measuring direction perpendicular to the moving axis 12 is greater than the width of the surrounding body 516 of the first surrounding member 510 in the measuring direction. Correspondingly, the width of the elastic wave body 626 of the second elastic wave 620 measured in the measuring direction is greater than the width of the surrounding body 526 of the second surrounding member 520 in the measuring direction. Figure 3, the width of the first surround body 516 (upper double arrow) and the width of the first elastic wave body 616 (lower double arrow) are illustrated.
[0082] The housing 100 includes a first housing portion 110, a second housing portion 120 and a third housing portion 130. The third housing portion 130 is located between the first housing portion 110 and the second housing portion 120. In use, the first diaphragm 210 radiates sound from the first housing portion 110, while the second diaphragm 220 radiates sound from the second housing portion 120.
[0083] The first surround 510 is attached to the first shell portion 110. The second surround 520 is attached to the second shell portion 120. More specifically, the outer tab 512 of the first surround 510 is attached to the first shell portion 110 at the first surround landing surface 111 on the shell 100, and the outer tab 522 of the second surround 520 is attached to the second shell portion 120 at the second surround landing surface 121.
[0084] The outer tab 612 of the first damper 610 is attached to the third shell portion 130 at the first damper landing surface 131 on the third shell portion 130. The outer tab 622 of the second damper 620 is attached to the third shell portion 130 at the second damper landing surface 132 on the third shell portion 130.
[0085] The center of mass of the translatable part 312 of the first drive unit 310 has a position between the first surround landing surface 111 and the first spring-damper landing surface 131 along the movement axis 12. That is, the first surround landing surface 111 and the first spring-damper landing surface 131 are separated along the movement axis 12, and the center of mass of the translatable part 312 is located between them. Similarly, the center of mass of the translatable part 322 of the second drive unit 320 has a position between the second surround landing surface 121 and the second spring-damper landing surface 132 along the movement axis 12.
[0086] The first shell portion 110 and the second shell portion 120 are respectively connected to the third shell portion 130. The first shell portion 110 and the third shell portion 130 are connected together at a position outward from the external tab 612 of the first damper 610. Similarly, the second shell portion 120 and the third shell portion 130 are connected together at a position outward from the external tab 622 of the second damper 620.
[0087] Each moving assembly 410, 420 includes a sleeve 412, 422, namely a first sleeve 412 and a second sleeve 422. The sleeves 412, 422 provide a structure for attaching the moving assembly 412, 420 to the spider 610, 620. Suitably, the sleeves 412, 422 extend along the axis of movement 12 and extend around at least a portion of the translatable parts 312, 322 and the fixed parts 311, 321 of the drive unit 310, 320. The inner tab 614 of the first spider 610 is attached to the first sleeve 412, while the inner tab 624 of the second spider 620 is attached to the second sleeve 422. In this example, the translatable parts 312, 322 include voice coils 316, 326 carried on voice coil formers 317, 327. Thus, the voice coil 316, 326 is connected to the sleeve 412, 422, which is further connected to the diaphragm 210, 220 and the spider 610, 620. The diaphragm 210, 220 connects the sleeve 412, 422 to the surround 510, 610, which acts as a first suspension element relative to the housing 100. The spider 610, 620 connects the sleeve 412, 422 to the housing 100 and acts as a second suspension element. The arrangement using the sleeve 412, 422 and the spider inner diameter radially outside the U-shaped yoke allows for a shallow loudspeaker design and excellent roll stability because the center of mass of the translatable part 312, 322 is between the two corresponding landing surfaces 111, 121, 131, 132.
[0088] The first sleeve 412 defines a plurality of first ventilation holes 414 to enable airflow through the first sleeve 412 in a direction generally perpendicular to the movement axis 12. Likewise, the second sleeve 422 is provided with a plurality of second ventilation holes 424 to enable airflow through the second sleeve 422.
[0089] Each voice coil former 317 , 327 forms a plurality of ventilation holes 318 , 328 to enable airflow to pass through the voice coil former 317 , 327 in a direction generally perpendicular to the axis of movement 12 .
[0090] A plurality of ventilation holes 618, 628 are formed by the damper bodies of the first damper 610 and the second damper 620. The ventilation holes 618, 628 are provided to enable airflow through the dampers 610, 620. The ventilation holes 618, 628 may be provided by a particularly open damper braid.
[0091] The vents in the voice coil formers 317, 327, the lower portions of the sleeves 412, 422, and the spiders 618, 628 can increase airflow between the volumes below the dust cover, between the diaphragms 210, 220 and the spiders 610, 620, and between the spiders 610, 620 and the symmetry plane 14. This arrangement can reduce internal blowing noise generated by air rushing through the air gap and spiders 618, 628 during operation.
[0092] exist Figure 3 and Figure 4 , the static position and the maximum displacement position of the first moving assembly 410 are illustrated. More specifically, Figure 3 The first moving assembly 410 is shown in a stationary position, while Figure 4 The first moving assembly 410 is shown in a maximum displacement position.
[0093] The woofer system 10 is operable to move the first movable component 410 from a rest position to a maximum displacement position, thereby causing a deflection (or "deformation") of the first spring wave 610. The maximum spring wave deflection angle α is defined as the angle formed between the first line and the second line. When the first movable component 410 is at rest, the first line extends between the outer protrusion 612 of the first spring wave 610 (e.g., the innermost position of the outer protrusion 612) and the inner protrusion 614 of the first spring wave 610 (e.g., the outermost position on the inner protrusion 614). When the first movable component 410 is in its maximum displacement position, the second line extends between the same positions of the outer protrusion 612 and the inner protrusion 614 of the first spring wave 620. These positions are on the same side of the moving axis 12, i.e., the first line and the second line do not extend to the other side of the speaker system 10. The first line and the second line extend in a plane containing the moving axis 12.
[0094] The maximum spring wave deflection angle α is preferably no greater than 25 degrees.
[0095] The two moving assemblies 410, 420 of the loudspeaker system 10 are mounted in a housing 100 in a symmetrical arrangement in a back-to-back configuration about a symmetry plane 14 perpendicular to the axis of movement 12 (or "main radiation axis"). The moving assemblies 410, 420 radiate sound in equal magnitude but in opposite directions when excited. The acoustic volume within the housing 100 can be common, i.e. shared by the two moving assemblies 410, 420, or divided at the symmetry plane 14.
[0096] The speaker system 10 allows for large spiders 610, 620 with improved linearity while still operating with low-cost conventional materials. The outer diameter of the spiders 610, 620 is increased to attach to the housing 100, thereby exceeding the size of the surrounds 510, 520. Therefore, even when increasing the inner diameter of the spider, the inner diameter can be increased without adversely affecting the linearity of the intended displacement of the spider. In this example, the relatively large outer diameter of the spider allows the spiders 610, 620 to have a linearity exceeding the 10 mm (millimeter) displacement produced by the drive units 310, 320, and thus provides clear and powerful bass reproduction.
[0097] The space enclosed by the inner diameter of the spider allows for a large voice coil and a large magnet inside the voice coil. The use of a large internal ferrite magnet allows for a low cost solution with a usable driver unit strength suitable for the intended application. Also, a U-yoke magnet system with the magnet located inside the voice coil is inherently more efficient than a T-yoke magnet system because there is relatively little leakage flux on the outer diameter of the magnet. Also, the number of windings and winding layers on the voice coil can be increased and a relatively wide air gap and increased magnetic circuit reluctance can be utilized. The relatively small total flux in the magnetic circuit allows for thin gaskets and U-yokes with thin wall thicknesses, keeping the overall mass of the motor system low. The density of ferrite is approximately 5 g / cm less than that of steel. 3 , so a motor system using more ferrite and less steel in the flux guiding elements can be surprisingly lightweight.
[0098] In this example, the ferrite magnet has a BHmax = 30 kJ / m 3 (kilojoules / cubic meter) maximum energy product and residual flux density of Br = 0.4 T (Tesla). The diameter is 50 mm (millimeters) and the height is 20 mm. The voice coil is wound from 0.43 mm copper wire and the winding height in 8 layers is 17 mm. This results in a force factor of 7.5 Tm (Tesla*meter) at rest and a motor linearity within ±10 mm of 50% (percent) of the force factor at rest.
[0099] The manufacturing process can be very similar to that of a conventional loudspeaker. In this example, the loudspeaker system 10 is built integrally with the housing 100 when constructed. First, the flux guides 314, 315, 324, 325 and the magnet system of the permanent magnets 313, 323, the voice coils 316, 326, the sleeves 412, 422 and the spiders 610, 620 are mounted in the third housing part 130 providing the axial center portion. Then, the parts 110, 120 of the housing 100 away from the symmetry plane 14 are placed and attached to the third part 130 by means of an adhesive. This division of the housing 100 can improve the assembly in which the outer diameter of the surround is smaller than the inner diameter of the spider. Or in other words, in which the spider extends further than the surround. This allows the use of large linear spiders at low axial stiffness while providing good radial centering, thereby effectively preventing the voice coil from rocking or rubbing relative to fixed parts. This arrangement is particularly useful for loudspeakers having large, low-cost magnets and therefore large voice coils, where the radial distance between the bottom end of the inner cone and the outer diameter of the surround becomes very small.
[0100] As can be understood from the above description, the manufacturing process of the speaker system 10 may not be more difficult than the manufacturing process of a conventional speaker. In fact, during the placement of the spiders 610, 620 and the guiding and shaping of the leads, the connection of the voice coils 316, 326 to the terminals, the exterior 110, 120 of the housing 100 may preferably be absent. If the magnet systems 314, 315, 324, 325 are built in last and the assembly of the translatable parts 410, 420 is performed on a jig, the dust cover portion may be integrated with the sleeves 412, 422 and the number of parts is thus reduced compared to conventional speaker constructions. Figure 2 In the embodiment of the present invention, the dust cover portion of the sleeve 412, 422 has a dome shape and can be made relatively thin and rigid. The diaphragms 210, 220 have a large inner diameter and can be made rigid, for example, by a steep taper angle. All structural connections are on relatively large diameters, and the stress on the structural connections is small. In this example, the structural connections are formed with glue so that the forces are distributed over a long, circumferential bead of glue.
[0101] Conventionally it can be assumed that in small boxes the stiffness of the box dominates the mechanical stiffness. While this may be true around the resting position, for larger displacements leading to compressed music reproduction, the spring with a small radial distance between the inner and outer diameters is usually non-linear. The mechanical stiffness may be 4 N / mm (Newtons / millimeter) and is so small compared to the stiffness of the box: 112 cm in a 2 liter 2 (square centimeters) of effective cone area adds an additional 10N / mm. However, this 10N / mm is very linear with displacement and hardly produces any audible distortion. However, a mechanical suspension using too small a spring will quickly rise from 4N / mm to 16N / mm, and will rise even further for displacements greater than 4mm to 5mm. This sharp rise prevents faithful musical reproduction and causes undesirable distortion.
[0102] The dampers 610, 620 in the illustrated arrangement are made of conventional materials, such as woven cloth impregnated with a thermosetting resin and baked into shape, but any suitable material may be used. Their design and function are well known to those skilled in the art. For example, the larger size allows the use of low-cost materials such as Polycotton instead of Kevlar (TM), and may wear more slowly and to a lesser extent than small dampers that are subjected to the heavy stress of large displacements in operation.
[0103] The permanent magnets 313, 323 are configured as ferrite magnets. Since the spiders 610, 620 can accommodate large magnets without adversely affecting the desired linearity of the spiders 610, 620, the use of large internal ferrite magnets allows for a low cost solution with available driver strength suitable for the intended application.
[0104] Figure 5 is a cross-sectional view of another exemplary bass speaker system 20. The speaker system 20 is Figure 2 , Figure 3 , Figure 4 The same reference numerals are used for corresponding features, and detailed description of these features is omitted.
[0105] According to the example of the speaker system 20, the first housing portion 110 and the second housing portion 120 meet when assembled. Therefore, although the housing 100 includes more than two shells joined together, a single dividing line is visible, rather than multiple dividing lines. Alternatively, other known techniques for avoiding visible dividing lines can be used, such as hot plate welding, ultrasonic welding, etc., which are well known in the industry and are widely available techniques.
[0106] When assembling the speaker system 20 , the insertion of the magnet system may be the last step before joining the housing portions 110 , 120 to the complete assembly of the speaker system 20 .
[0107] Each diaphragm 210, 220 includes a separate dust cover 214, 224. The dust cover 214, 224 covers the drive unit 310, 320 which would otherwise be exposed in use.
[0108] The U-shaped yoke 315, 325 of the fixed parts 311, 321 of each drive unit 310, 320 includes a base 319A and a wall 319B extending from the base. In this example, the first U-shaped yoke 315 and the second U-shaped yoke 325 are arranged in a back-to-back configuration. More specifically, the base of the first U-shaped yoke 315 and the base of the second U-shaped yoke 315 are formed integrally, and the wall of the first U-shaped yoke 315 and the wall of the second U-shaped yoke 325 extend in opposite directions from the connected base. A single external flux guiding element formed by two U-shaped yokes 315, 325 arranged back to back (as in this example) can be called an H-shaped yoke.
[0109] Figure 6 is a cross-sectional view of another exemplary bass speaker system 30. The speaker system 30 and Figure 2 , Figure 3 , Figure 4 The same reference numerals are used for corresponding features, and detailed description of these features is omitted.
[0110] like Figure 6 As shown, the diaphragms 110, 120 are provided by the dust covers 214, 224. That is, the sound radiating surfaces 211, 221 are formed only by the dust covers 214, 224.
[0111] In this example, the dust cover 214, 224 is integrally formed with the sleeve 412, 422 to define a single structure that is directly connected to the voice coil former 317, 327, the surround 510, 520, and the spider 610, 620. In this case in particular, as described above, it may be beneficial to add radial vents that connect the air volume below the dust cover 214, 224 with the air volume above and below the spider 610, 620.
[0112] This example can very clearly illustrate the benefits of the speaker system 30 according to the present invention. Figure 6 In the configuration shown, there is no room for a conventional frame that would fit within housing 100 (which acts as a conventional box) and that would accommodate a useful spider of conventional shape. Figure 6 In the configuration, the inner landing surfaces of the surrounds 510, 520 are located at the voice coil formers 317, 327. This configuration is not possible with a tapered frame of conventional design.
[0113] Figure 7 is a cross-sectional view of another exemplary bass speaker system 40. The speaker system 40 is Figure 2 , Figure 3 , Figure 4 The same reference numerals are used for corresponding features, and detailed description of these features is omitted.
[0114] exist Figure 7 , what can be considered a completely different speaker system is shown, where the voice coil 316, 326 is fixed to the housing 100 and the magnet system is movable. It can be used with the cone, or as shown, the surround 510, 520 is directly connected to the U-yoke 315, 325. Again, the large outer diameter of the spider 610, 620 allows this arrangement to be useful and allows high linear displacement of a small effective cone area in a small box with a very low resonant frequency.
[0115] like Figure 7 As shown, the diaphragms 110, 120 correspond to the flux guides 315, 325. That is, the sound radiating surfaces 211, 221 are formed only by the flux guides 315, 325.
[0116] In this example, the first surround 510 and the first damper 610 are both attached to the first housing portion 110 , while the second surround 520 and the second damper 620 are both attached to the second housing portion 120 .
[0117] Figure 8 is a cross-sectional view of another exemplary bass speaker system 50. The speaker system 50 is Figure 2 , Figure 3 , Figure 4The same reference numerals are used for corresponding features, and detailed description of these features is omitted.
[0118] exist Figure 8 In , yet another arrangement according to the invention is shown. As in the previous arrangement, the radiating axis 12 is common and the moving components 410, 420 radiate the same amount of sound in opposite directions. The design is still force-canceling, but the interaction via the magnet system is not as immediate as when they are linked together. Suitably, the housing is constructed to be more rigid than the previous arrangement. The moving components radiate into a common cavity 102 which is then vented to the outside. Again, the outer diameter of the spider 610, 620 is greater than the outer diameter of the surrounds 510, 520.
[0119] Fig. 9 is a schematic diagram of a vehicle 2000 including a bass speaker system 10. Any of the exemplary speaker systems described above may be installed in the vehicle 2000. In this example, the speaker system 10 described above is disposed between the footwells 2100 of the vehicle 2000. Other locations are also contemplated, such as at or toward the bottom of the A-frame.
[0120] The above-described woofer system has a circularly symmetric moving assembly. In other examples, other shapes for at least some of the components are also contemplated. For example, the diaphragm and surround may have a racetrack shape or an elliptical shape, while the translatable parts of the drive unit and the elastic wave may be circularly symmetric. As in the above-described arrangement, the size of the elastic wave body 616, 626 exceeds the size of the surround body 516, 526, but this may be done in some directions but not all directions. Preferably, the size of the elastic wave body 616, 626 exceeds the size of the surround body 516, 526 in the direction in which the surround body 616, 626 is narrower.
[0121] Different arrangements have been described above, for example with and without a diaphragm, with and without a separate dust cover. Furthermore, the magnet material of the permanent magnets can be freely chosen, since the invention allows the use of even relatively large ferrite sheets (but is not limited thereto).
[0122] The speaker systems 10, 20, 30, 40, 50 may have in common some / all of the following aspects:
[0123] - A loudspeaker system for reproducing music from an even number of moving components (the system may be substantially in accordance with Figure 2 or Figure 6 The concept stack described in .
[0124] - All moving components share a common main radial axis and thus a basic axis of symmetry.
[0125] - All moving components are substantially identical and are pairwise symmetrical about a symmetry plane perpendicular to the main radiation axis.
[0126] - All moving components are excited with approximately the same low frequency signal (eg within the operating range from 20 Hz to 200 Hz).
[0127] - The loudspeaker system is arranged so that the mechanical forces cancel out and the fixed parts of the system are effectively free from vibrations.
[0128] - Each speaker system may include a housing integral with a speaker frame and a plurality of each of the following components:
[0129] A magnet system consisting of at least one permanent magnet and at least two flux guiding elements;
[0130] Voice coil;
[0131] Surrounding parts;
[0132] A spring wave, the fixed diameter of which is larger than the fixed diameter of the surrounding member.
[0133] The features disclosed in the above description or the attached claims or drawings (expressed in their specific form or according to the device for performing the disclosed function, or the method or process for obtaining the disclosed result) can be used to realize the present invention in its different forms, either alone or in any combination of these features.
[0134] Although the present invention has been described in conjunction with the above exemplary embodiments, many equivalent modifications and variations will be clear to those skilled in the art when the present invention is given. Therefore, the above exemplary embodiments of the present invention are considered 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.
[0135] 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.
[0136] Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described.
[0137] Throughout the specification, including the following claims, unless the context requires otherwise, the words "comprises" and "comprising" and variations thereof 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.
[0138] It must be noted that, as used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural references 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 one particular value and / or to the other particular value. Similarly, when a value is expressed as an approximation by using the antecedent "about", it should be understood that the particular value forms another embodiment. The term "about" in relation to a numerical value is optional and refers to, for example, + / - 10%.
Claims
1. A woofer speaker system, comprising: case; a first diaphragm and a second diaphragm; a first drive unit and a second drive unit, each drive unit comprising a translatable part and a fixed part attached to the housing; wherein the translatable part of the first drive unit is attached to the first diaphragm to form a first moving assembly suspended from the housing through a first surround and a first spring, and the translatable part of the second drive unit is attached to the second diaphragm to form a second moving assembly suspended from the housing through a second surround and a second spring; wherein the speaker is operable to excite the first drive unit and the second drive unit so that the first moving component and the second moving component move in opposite directions along a moving axis to generate sound; wherein the first surround comprises an outer protrusion attached to the housing, an inner protrusion attached to the first diaphragm, and a surround body between the outer protrusion and the inner protrusion; wherein the second surround comprises an outer protrusion attached to the housing, an inner protrusion attached to the second diaphragm, and a surround body between the outer protrusion and the inner protrusion; wherein the first spring wave comprises an external protrusion attached to the housing, an internal protrusion attached to the first moving component, and a spring wave body between the external protrusion and the internal protrusion; wherein the second spring wave comprises an external protrusion attached to the housing, an internal protrusion attached to the second moving assembly, and a spring wave body between the external protrusion and the internal protrusion; wherein the width of the first spring wave body measured in a measuring direction perpendicular to the moving axis is greater than the width of the surround body of the first surround in the measuring direction; and Wherein, the width of the elastic wave body of the second elastic wave measured in the measuring direction is greater than the width of the surrounding member body of the second surrounding member in the measuring direction.
2. The woofer speaker system according to claim 1, wherein: The measuring direction corresponds to a direction in which the width of the spring body of the first spring is shortest.
3. The woofer speaker system according to claim 1 or 2, wherein: The outer tab of the first surround is attached to the shell at a first surround landing surface on the shell; and the outer tab of the first damper is attached to the shell at a first damper landing surface on the shell; and Wherein, the center of mass of the translatable part of the first driving unit has a position along the movement axis between the first surround landing surface and the first spring landing surface.
4. A woofer system according to any one of the preceding claims, in, The woofer system is operable to move the first movable assembly from a rest position to a maximum displacement position, thereby causing deflection of the first spider; Where the maximum spring deflection angle is defined as the angle formed between: a first line extending between an innermost position on the outer tab of the first damper and an outermost position on the inner tab of the first damper when the first moving assembly is stationary; and a second line extending between the same innermost position on the outer tab of the first damper and the same outermost position on the inner tab of the first damper when the first moving component is in its maximum displacement position; wherein the innermost position on the outer tab of the first damper and the outermost position on the inner tab of the first damper are on the same side of the movement axis; and The first line and the second line extend in a plane containing the movement axis; Wherein, the maximum elastic wave deflection angle is no greater than 25 degrees.
5. A woofer system according to any one of the preceding claims, in, The first drive unit comprises a permanent magnet and a plurality of flux guiding elements; Therein, the mass of the flux guiding element is in the range of 0.8 to 1.2 times the mass of the permanent magnet.
6. A woofer system according to any one of the preceding claims, wherein: The housing comprises a first housing portion, a second housing portion and a third housing portion between the first housing portion and the second housing portion; the first surround being attached to the first housing portion; The first spring is attached to the first shell portion or the third shell portion; and The fixing part of the first drive unit is attached to the third housing part.
7. The woofer speaker system according to claim 6, in, The first shell portion and the third shell portion are joined together at a location outward from the outer tab of the first damper.
8. A woofer loudspeaker system according to any one of the preceding claims, in, The first drive unit comprises a first U-shaped yoke, and the second drive unit comprises a second U-shaped yoke, each U-shaped yoke comprising a base and a wall extending from the base; Wherein, the base of the first U-shaped yoke and the base of the second U-shaped yoke are formed integrally.
9. A woofer loudspeaker system according to any one of the preceding claims, wherein: The translatable part of the first drive unit includes a voice coil; The first moving assembly comprises a first sleeve extending along the movement axis and surrounding the voice coil and at least a portion of the fixed part of the first drive unit; Wherein, the inner protrusion of the first spider is attached to the sleeve of the first moving component.
10. The woofer speaker system according to claim 9, in, The first sleeve defines a plurality of first ventilation holes therethrough to enable airflow through the first sleeve in a direction generally perpendicular to the axis of movement; and The voice coil former of the translatable part of the first drive unit forms a plurality of second ventilation holes therethrough, so that air can pass through the voice coil former in a direction substantially perpendicular to the movement axis.
11. The woofer speaker system according to any one of claims 1 to 7, wherein: The translatable part of the first drive unit comprises a permanent magnet and a flux guiding element.
12. The woofer speaker system according to claim 11, wherein The flux guiding element serves as the first diaphragm, and the inner tab of the first damper is attached to the flux guiding element.
13. A woofer loudspeaker system according to any one of the preceding claims, in, The first damper is arranged to divide the interior volume of the housing into a first volume at one side of the first damper and a second volume at another side of the first damper; The first damper forms a plurality of ventilation holes therethrough, so that airflow can pass through the first damper.
14. A woofer loudspeaker system according to any one of the preceding claims, in, The first driving unit includes a ferrite magnet.
15. A woofer loudspeaker system according to any one of the preceding claims, wherein: The first driving unit includes a voice coil, a permanent magnet, and a plurality of flux guiding elements, and a mass of the permanent magnet of the first driving unit is smaller than a mass of the voice coil of the first driving unit.
16. A vehicle comprising a woofer system according to any one of the preceding claims.