Passive radiator unit and loudspeaker system including the same

Abstract

The present invention provides a passive radiator unit and a loudspeaker system including the passive radiator unit. The passive radiator unit includes: a first passive radiator, which includes a first moving mass; a second passive radiator, opposite to the first passive radiator, the second passive radiator including a second moving mass; and a connection structure connected between the first moving mass of the first passive radiator and the second moving mass of the second passive radiator. The connection structure is configured to have a radial stiffness greater than its axial stiffness, so as to prevent rocking motion while allowing the first passive radiator and the second passive radiator to vibrate axially normally.

Description

Technical Field

[0001] The present invention relates to the field of loudspeaker systems, and particularly to a passive radiator unit and a loudspeaker system including the passive radiator unit. Background Art

[0002] Passive radiator units are a well-known method for implementing the bass reflex principle in loudspeakers. Their important advantage is that they can implement the bass reflex principle in a very small enclosed space. Due to the port size (unrealistically narrow or unrealistically long), it is not possible to implement a more traditional bass reflex loudspeaker with a port as the radiation structure. Recent experiments on mobile phone loudspeakers have shown that using passive radiator unit technology is feasible and indeed brings significant benefits in terms of the low-frequency range, distortion, and the maximum sound pressure available.

[0003] Although somewhat functional, a simple passive radiator enclosure (with a mass and an outer edge suspension) consisting of a driver, a cavity, and a single passive radiator has some implementation-related challenges. The first is that the volume displacement (surface area * displacement) of the passive radiator is preferably much larger than the volume displacement (surface area * displacement) of the loudspeaker driver. The second is that if the system is subjected to an external mechanical shock (such as dropping from a device), it generates a pressure pulse in the cavity, which may damage the driver (this is a problem, especially for portable devices). In addition, since the moving mass of the passive radiator is usually greater than that of the driver, the vibration of the passive radiator generates a stronger reaction force on the device at low frequencies than other types of loudspeakers (ported reflex or sealed enclosures), although this can be used as an alarm system.

[0004] These problems can be solved by symmetrically using two identical passive radiators on both sides of the enclosure. This can solve the above problems: it is easy to increase the area of the passive radiator. If the device drops, the pressure pulses generated by the two radiators will cancel each other out. During normal use, the movement directions of the two passive radiators are opposite, and no net vibration force is generated on the device housing.

[0005] However, the symmetric radiator structure does not eliminate all the problems that occur when applying passive radiators to devices with very small form factors. Due to the large moving mass block of the passive radiator, only a simple support mechanism at the outer edge, and the uneven sound fields inside and outside the radiator, the passive radiator is prone to rocking vibration, which increases the distortion of the radiator, resulting in narrowband irregularities in the frequency response and reducing the available maximum displacement. The strong rocking mode also increases mechanical fatigue in the environment, thus reducing the lifespan of the device.

[0006] Therefore, what is needed is a mechanical device that can eliminate or suppress the rocking vibration of the passive radiator. Summary of the Invention

[0007] In view of this, an embodiment of the present invention provides a passive radiator unit and a speaker system including the passive radiator unit.

[0008] In a first aspect, an embodiment of the present invention provides a passive radiator unit, which includes:

[0009] A first passive radiator, including a first moving mass block;

[0010] A second passive radiator, opposite to the first passive radiator and including a second moving mass block;

[0011] A connection structure connected between the first moving mass block of the first passive radiator and the second moving mass block of the second passive radiator, the connection structure being configured to have a radial stiffness greater than its axial stiffness, thereby preventing rocking motion while allowing the first passive radiator and the second passive radiator to vibrate axially normally.

[0012] In one embodiment, the connection structure includes:

[0013] A flexible member located between the first moving mass block and the second moving mass block;

[0014] A first connection member connecting the flexible member and the first moving mass block;

[0015] A second connection member connecting the flexible member and the second moving mass block.

[0016] In one embodiment, the flexible member has a center and an outer edge, the first connection member is connected to the center of the flexible member, and the second connection member is connected to the outer edge of the flexible member.

[0017] In one embodiment, the first connection member is a connecting rod or a connecting tube, and the second connection member is a connecting ring.

[0018] In one embodiment, the connecting ring is perforated to prevent the deformation of the air spring between the flexible member and the second moving mass block.

[0019] In one embodiment, the flexible member includes one of the following two: a flexible plate having circumferential corrugations arranged radially from the center to the outer edge and a thin plate provided with a notch between the center and the outer edge.

[0020] In one embodiment, the connection structure further includes a spring structure connecting the flexible member to a fixed point outside the edges of the first and second passive radiators, the fixed point being configured to be fixed relative to the housing for mounting the passive radiator unit.

[0021] In one embodiment, the spring structure includes a plurality of leaf springs.

[0022] In one embodiment, the flexible member has a center and an outer edge, the first connecting member is connected to the center of the flexible member, the second connecting member is connected to a region of the flexible member within the outer edge, the outer edge extends to a fixed point and is supported by the fixed point, and the fixed point is configured to be fixed relative to the housing for mounting the passive radiator unit.

[0023] In one embodiment, the connecting structure includes a rod structure that ensures parallel movement of the first passive radiator and the second passive radiator along the axis of the passive radiator unit.

[0024] In one embodiment, the rod structure includes at least one hinge-rod device, and each hinge-rod device includes:

[0025] A first rod portion including a first rigid rod and a second rigid rod each having two opposite rod ends, one rod end of the first rigid rod is connected to the first moving mass block through a first hinge, one rod end of the second rigid rod is connected to the second moving mass block through a second hinge, and the other rod ends of the first rigid rod and the second rigid rod are connected together through a third hinge, wherein the first hinge defines a first rotation axis perpendicular to the axis and is configured to allow the first rigid rod to rotate relative to the first moving mass block only about the first rotation axis, the second hinge defines a second rotation axis perpendicular to the axis and is configured to allow the second rigid rod to rotate relative to the second moving mass block only about the second rotation axis, and the third hinge defines a third rotation axis perpendicular to the axis and is configured to allow the first rigid rod and the second rigid rod to rotate only relative to the third rotation axis;

[0026] A second rod portion includes a third rigid rod and a fourth rigid rod each having two opposite rod ends. One rod end of the third rigid rod is connected to the first moving mass block through a fourth hinge, and one rod end of the fourth rigid rod is connected to the second moving mass block through a fifth hinge. The other rod ends of the third rigid rod and the fourth rigid rod are connected together through a sixth hinge. Wherein the fourth hinge defines a fourth rotation axis perpendicular to the axial rotation and is configured to allow the third rigid rod to rotate relative to the first moving mass block only about the fourth rotation axis. The fifth hinge defines a fifth rotation axis perpendicular to the axial direction and is configured to allow the fourth rigid rod to rotate relative to the second moving mass block only about the fifth rotation axis. The sixth hinge defines a sixth rotation axis perpendicular to the axial direction and is configured to allow the third rigid rod and the fourth rigid rod to rotate relative to each other only about the sixth rotation axis, and the first to sixth rotation axes are parallel to each other; and

[0027] A rigid connecting rod having two opposite rod ends, one rod end of the connecting rod is connected to the third hinge such that the first rigid rod, the second rigid rod, and the connecting rod can rotate relative to each other about the third rotation axis, and the other rod end of the connecting rod is connected to the sixth hinge such that the third rigid rod, the fourth rigid rod, and the connecting rod can rotate relative to each other about the sixth rotation axis.

[0028] In one embodiment, the at least one hinge-rod device includes one hinge-rod device, and each of the first to sixth hinges extends along its respective rotation axis beyond approximately the entire length of the first and second moving mass blocks.

[0029] In one embodiment, the at least one hinge-rod device includes a plurality of hinge-rod devices arranged along the outer edges of the first and second moving mass blocks.

[0030] In a second aspect, the present invention further provides a speaker system, including:

[0031] A sound-insulating housing including a first wall and a second wall opposite to each other; and

[0032] A driver and a passive radiator unit, the passive radiator unit is mounted on the sound-insulating housing, and the passive radiator unit includes:

[0033] A first passive radiator mounted on the first wall and including a first moving mass block;

[0034] A second passive radiator mounted on the second wall and aligned with the first passive radiator; the second passive radiator includes a second moving mass block; and

[0035] A connecting structure is connected between a first moving mass of the first passive radiator and a second moving mass of the second passive radiator. The connecting structure is configured to have a radial stiffness greater than an axial stiffness, thereby preventing rocking motion while allowing the first passive radiator and the second passive radiator to vibrate normally axially.

[0036] In one embodiment, the connecting structure includes:

[0037] A flexible member located between the first moving mass and the second moving mass;

[0038] A first connecting member connecting the flexible member and the first moving mass; and

[0039] A second connecting member connecting the flexible member and the second moving mass.

[0040] In one embodiment, the flexible member includes a flexible plate having a center and an outer edge. The flexible plate has circumferential corrugations arranged radially from the center to the outer edge. The first connecting member is connected to the center of the flexible plate, and the second connecting member is connected to the outer edge of the flexible plate.

[0041] In one embodiment, the first connecting member is a connecting rod or a connecting tube, and the second connecting member is a connecting ring. The connecting ring is perforated to prevent the deformation of the air spring between the flexible member and the second moving mass.

[0042] In one embodiment, the connecting structure further includes a spring structure connecting the flexible member to a fixed point. The fixed point is located outside the edge of the second passive radiator and is fixed relative to the sound insulation housing.

[0043] In one embodiment, the flexible member has a center and an outer edge. The first connecting member is connected to the center of the flexible member, and the second connecting member is connected to a region of the flexible member. The region is located inside the outer edge and is spaced apart from the outer edge. The outer edge extends to the fixed point and is supported by the fixed point. The fixed point is fixed relative to the sound insulation housing.

[0044] In one embodiment, the connecting structure includes a rod structure that ensures the axial parallel movement of the first passive radiator and the second passive radiator in the passive radiator unit. The rod structure includes at least one hinge-rod device, and each hinge-rod device includes:

[0045] The first rod portion includes a first rigid rod and a second rigid rod each having two opposite rod ends. One rod end of the first rigid rod is connected to the first moving mass block through a first hinge, and one rod end of the second rigid rod is connected to the second moving mass block through a second hinge. The other rod ends of the first rigid rod and the second rigid rod are connected together through a third hinge. Wherein the first rigid rod defines a first rotation axis perpendicular to the axial direction and is configured to allow the first rigid rod to rotate relative to the first moving mass block only about the first rotation axis. The second hinge defines a second rotation axis perpendicular to the axial direction and is configured to allow the second rigid rod to rotate relative to the second moving mass block only about the second rotation axis. The third hinge defines a third rotation axis perpendicular to the axial direction and is configured to allow the first rigid rod and the second rigid rod to rotate relative to each other only about the third rotation axis;

[0046] The second rod portion includes a third rigid rod and a fourth rigid rod each having two opposite rod ends. One rod end of the third rigid rod is connected to the first moving mass block through a fourth hinge, and one rod end of the fourth rigid rod is connected to the second moving mass block through a fifth hinge. The other rod ends of the third rigid rod and the fourth rigid rod are connected together through a sixth hinge. Wherein the fourth hinge defines a fourth rotation axis perpendicular to the axial direction and is configured to allow the third rigid rod to rotate relative to the first moving mass only about the fourth rotation axis. The fifth hinge defines a fifth rotation axis perpendicular to the axial direction and is configured to allow the fourth rigid rod to rotate relative to the second moving mass block only about the fifth rotation axis. The sixth hinge defines a sixth rotation axis perpendicular to the axial direction and is configured to allow the third rigid rod and the fourth rigid rod to rotate relative to each other about the sixth rotation axis, and the first to sixth rotation axes are parallel to each other; and

[0047] A rigid connecting rod having two opposite rod ends. One rod end of the connecting rod is connected to the third hinge such that the first rigid rod, the second rigid rod, and the connecting rod can rotate relative to each other about the third rotation axis. The other rod end of the connecting rod is connected to the sixth hinge such that the third rigid rod, the fourth rigid rod, and the connecting rod can rotate relative to each other about the sixth rotation axis.

[0048] Embodiments of the present invention provide a passive radiator unit and a speaker system using the passive radiator unit. The passive radiator unit includes a connection structure connecting two passive radiators, and the connection structure allows the radiator diaphragm to vibrate normally while preventing harmful rocking motion. The connection structure can be implemented in many different ways. For example, the connection structure may include a flexible member located between a first moving mass and a second moving mass, a first connection member connecting the flexible member to the first moving mass, and a second connection member connecting the flexible member to the second moving mass. The flexible member can be a corrugated flexible plate or a thin plate provided with cutouts. The central portion of the flexible member can be further supported at a fixed point outside the radiator edge, such that the connection structure is very effective for both the asymmetric rocking mode and the symmetric rocking mode of the radiator. The connection structure can also be a rod structure, ensuring that the first passive radiator and the second passive radiator move parallel in the axial direction of the passive radiator unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a schematic structural diagram of a speaker system according to a first embodiment of the present invention;

[0050] Figure 2 is Figure 1 a side view of a first embodiment of the passive radiator unit of the speaker system shown;

[0051] Figure 3 is Figure 2 a schematic diagram of the passive radiator unit shown with the first radiator removed;

[0052] Figure 4 is Figure 1 a side view of a second embodiment of the passive radiator unit of the speaker system shown;

[0053] Figure 5 is Figure 4 a schematic diagram of the passive radiator unit shown with the first radiator removed;

[0054] Figure 6 is Figure 1 a side view of a third embodiment of the passive radiator unit of the speaker system shown;

[0055] Figure 7 is Figure 6 a schematic diagram of the passive radiator unit shown with the first radiator removed;

[0056] Figure 8 is Figure 1 a side view of a fourth embodiment of the passive radiator unit of the speaker system shown;

[0057] Figure 9 is Figure 8Schematic diagram of the passive radiator unit shown with the first radiator removed;

[0058] Figure 10 is Figure 1 Side view of the fifth embodiment of the passive radiator unit of the loudspeaker system shown;

[0059] Figure 11 is Figure 10 Schematic diagram of the passive radiator unit shown with the first radiator removed;

[0060] Figure 12 is Figure 1 Side view of the sixth embodiment of the passive radiator unit of the loudspeaker system shown;

[0061] Figure 13 is Figure 12 Schematic diagram of the passive radiator unit shown with the first radiator removed. Detailed implementation manner

[0062] Generally speaking, the present invention relates to a passive radiator unit and a loudspeaker system using the passive radiator unit. The passive radiator unit may include a connection structure connecting two passive radiators, and this connection structure can prevent harmful rocking motion while allowing normal vibration of the radiator diaphragm.

[0063] Figure 1 A loudspeaker system 10 according to an embodiment of the present invention is shown. The loudspeaker system 10 generally includes a sound-insulating housing 12 defining an internal cavity 14, and a driver 16 and a passive radiator unit 18 mounted on the housing 12. As is well known, the physical forward / backward movement of the driver 16 affects the internal air pressure of the housing 12, and the fluctuation of the internal air pressure causes the passive radiator unit 18 to start vibrating along the axis of the passive radiator unit 18, thereby generating an audio frequency. The loudspeaker system 10 in the present invention can be implemented as an independent loudspeaker. Alternatively, the loudspeaker system 10 can also be embedded in a portable electronic device, such as a mobile phone or a tablet computer.

[0064] The passive radiator unit 18 includes a first passive radiator 20, a second passive radiator 22 oppositely oriented to the first passive radiator 20; a connection structure 24 for connecting the first passive radiator 20 and the second passive radiator 22 to ensure that the first passive radiator 20 and the second passive radiator 22 move axially in parallel.

[0065] As shown in the figure, the housing 12 includes a first wall 26 and a second wall 28 that face each other. The first wall 26 defines a first opening 29, on which a first passive radiator 20 is mounted. Specifically, the first passive radiator 20 includes a first moving mass 30 connected to the inner edge of the radiator diaphragm, and a first outer edge suspension 32 connected to the outer edge of the radiator diaphragm. The first outer edge suspension 32 is fixed to the edge of the first opening 29. Similarly, the second wall 28 defines a second opening 34, and a second passive radiator 22 is mounted on the second opening 34. The first passive radiator 20 is aligned with the second passive radiator 22. The second passive radiator 22 includes a second moving mass 36 connected to the inner edge of the radiator diaphragm, and a second outer edge suspension 38 connected to the outer edge of the radiator diaphragm. The second outer edge suspension 38 is fixed to the edge of the second opening 34. For ease of illustration, the radiator diaphragm is not shown, or can be considered as part of the moving mass.

[0066] The connecting structure 24 is connected between the first moving mass 30 and the second moving mass 36. The connecting structure 24 has a very large radial stiffness and a very low axial stiffness. In other words, the connecting structure 24 is quite rigid in the radial direction while being compliant in the axial direction, thereby preventing unwanted rocking motion while allowing the first and second passive radiators 20, 22 to vibrate normally in the axial direction. The term "normal vibration" used in the present invention refers to the vibration of the radiator to generate sound frequencies in response to the physical forward / backward movement of the driver.

[0067] The connecting structure 24 can be implemented in many different ways, which will be discussed below in connection with various embodiments of the passive radiator unit 18.

[0068] Figure 2 and Figure 3 A first embodiment of the passive radiator unit 18 is shown. As described above, the passive radiator unit 18 includes a first passive radiator 20, a second passive radiator 22 opposite the first passive radiator 20, and a connecting structure 24 interconnecting the first passive radiator 20 and the second passive radiator 22. In this embodiment, the connecting structure 24 includes a flexible member 40 located between the first moving mass 30 and the second moving mass 36, a first connecting member 42 connecting the flexible member 40 to the first moving mass 30, and a second connecting member 44 connecting the flexible member 40 to the second moving mass 36.

[0069] In the illustrated embodiment, the flexible member 40 is implemented as a flexible plate having a center 46 and an outer edge 48. The flexible plate obtains flexibility through radial corrugations from the center 46 to the outer edge 48. The first connecting member 42 is connected to the center 46 of the corrugated flexible plate, and the second connecting member 44 is connected to the outer edge 48 of the corrugated flexible plate.

[0070] The first connecting member 42 can be a connecting rod or a connecting pipe. One end of the connecting rod or pipe is connected to the first moving mass 30, and the other end of the connecting rod or pipe is connected to the center 46 of the flexible plate. The second connecting member 44 can be a connecting ring that supports the outer edge 48 of the flexible plate. The connecting ring has opposite first and second ring sides 440, 442. The first ring side 440 is connected to the outer edge 48 of the flexible plate, and the second ring side 442 is connected to the second moving mass 36. The connecting ring can be perforated to prevent the formation of an air spring between the flexible plate and the second moving mass 36. The radial corrugations of the flexible plate make the flexible plate very compliant axially. The outer edge 48 of the flexible plate is connected to and supported by the connecting ring, so that the flexible plate has considerable rigidity in the radial direction. Due to the high rigidity of the flexible plate in the radial direction and the low rigidity in the axial direction, the connection structure 24 coupled between the first and second passive radiators 20, 22 can prevent unwanted rocking motion while allowing the first and second passive radiators 20, 22 to vibrate normally axially.

[0071] Figure 4 and Figure 5 FIG. shows a second embodiment of the passive radiator unit 18. The passive radiator unit 18 of the second embodiment is similar to the passive radiator unit 18 of the first embodiment, except for the flexible member 40. As Figure 4 and Figure 5 shown, the flexible member 40 of the passive radiator unit 18 of this embodiment is implemented as a thin plate with cutouts 50. The thin plate includes a center 52 and an outer edge 54. The cutouts 50 are defined and evenly distributed between the center 52 and the outer edge 54. The outer end 56 of each cutout 50 is spaced from the outer edge 54 by a distance, so that the outer edge 54 is a continuous structure. The purpose of the cutouts 50 is to make the thin plate very compliant axially. The outer edge 54 of the thin plate is connected to and supported by the connecting ring, making the thin plate rigid in the radial direction. Due to the high radial rigidity and low axial rigidity of the thin plate, the connection structure 24 coupled between the first and second passive radiators 20, 22 can prevent unwanted rocking motion while allowing the first and second passive radiators 20, 22 to vibrate normally axially. The thin plate allows for a very thin structure of the passive radiator unit, minimizing the extra space between the radiators. To obtain greater radial rigidity and lower axial rigidity, the thin plate can have many different structures, and the notched plate is just a schematic illustration.

[0072] Figure 6 and Figure 7 FIG. shows a third embodiment of the passive radiator unit 18. The passive radiator unit 18 of the third embodiment is similar to the passive radiator unit 18 of the foregoing embodiment, except for the flexible member 40. As Figure 6 and Figure 7As shown, the flexible member 40 has a center 60 and an outer edge 62, and has circumferential corrugations arranged from the center 60 to the outer edge 62. The first connecting member 42 is connected to the center 60 of the flexible member 40, and the second connecting member 44 is connected to a region 64 of the flexible member 40 that is located within and spaced from the outer edge 62. The outer edge 62 extends to and is supported by a fixed point 66 that is fixed relative to the sound insulation housing. By supporting the central portion of the flexible member 40 at the fixed point 66 outside the radiator edge, the stiffness of the connection structure 24 against torque at the center 60 is increased, making the connection structure very effective for both the asymmetric rocking mode and the symmetric rocking mode of the radiator. In a third embodiment, this is achieved by extending the corrugated flexible member 40 to the outside of the radiator, thereby creating a common bracket similar to that shared by two passive radiators.

[0073] In Figure 8 and Figure 9 the fourth embodiment shown, the connection structure 24 further includes a spring structure 70, such as a leaf spring, that connects the flexible member 40 to the fixed point 66 outside the radiator edge. Thus, the central portion of the flexible member 40 can also be supported at the external fixed point 66, and thus, the stiffness of the connection structure 24 against torque at the center 60 is also increased.

[0074] Figure 10 and Figure 11 A fifth embodiment of the passive radiator unit 18 is shown. Except for the connection structure 24, the passive radiator unit 18 of the fifth embodiment is similar to the passive radiator units of the foregoing embodiments. The connection structure 24 of the fifth embodiment includes a leveling mechanism that ensures parallel axial movement of the first passive radiator 20 and the second passive radiator 22 along the passive radiator unit 18. The leveling mechanism includes at least one hinge-rod device. Figure 10 and Figure 11An embodiment showing a single hinge-rod device as a four-bar linkage system is presented. However, it should be understood that other numbers of rods are possible as long as parallel movement of the first and second passive radiators can be achieved. In this particular embodiment, the hinge-rod device includes a first rod portion 72, a second rod portion 74, and a rigid connecting rod 76 connecting the first rod portion 72 and the second rod portion 74. The first rod portion 72 includes a first rigid rod 78 and a second rigid rod 80, both having two opposite rod ends. One rod end of the first rigid rod 78 is connected to the first moving mass 30 through a first hinge 82, and one rod end of the second rigid rod 80 is connected to the second moving mass 36 through a second hinge 84. The other rod ends of the first rigid rod 78 and the second rigid rod 80 are connected through a third hinge 86. The first hinge 82 defines a first rotation axis perpendicular to the axial direction and is configured to allow only the first rigid rod 78 to rotate relative to the first moving mass 30 about the first rotation axis. The second hinge 84 defines a second rotation axis perpendicular to the axial direction and is configured to allow only the second rigid rod 80 to rotate relative to the second moving mass 36 about the second rotation axis. The third hinge 86 defines a third rotation axis perpendicular to the axial direction and is configured to allow only the first rigid rod 78 and the second rigid rod 80 to rotate relative to each other about the third rotation axis.

[0075] The second rod portion 74 includes a third rigid rod 88 and a fourth rigid rod 90, both having two opposite rod ends. One rod end of the third rigid rod 88 is connected to the first moving mass 30 through a fourth hinge 92, and one rod end of the fourth rigid rod 90 is connected to the second moving mass 36 through a fifth hinge 94. The other rod ends of the third rigid rod 88 and the fourth rigid rod 90 are connected through a sixth hinge 96. The fourth hinge 92 defines a fourth rotation axis perpendicular to the axial direction and is configured to allow only the third rigid rod 88 to rotate relative to the first moving mass 30 about the fourth rotation axis. The fifth hinge 94 defines a fifth rotation axis perpendicular to the axial direction, and the fifth rotation axis is configured to allow only the fourth rigid rod 90 to rotate relative to the second moving mass 36 about the fifth rotation axis. The sixth hinge 96 defines a sixth rotation axis perpendicular to the axial direction and is configured to allow only the third rigid rod 88 and the fourth rigid rod 90 to rotate relative to each other about the sixth rotation axis. The first to sixth rotation axes are parallel to each other.

[0076] The rigid connecting rod 76 has two opposite rod ends. One rod end of the connecting rod 76 is connected to the third hinge 86 such that the first rigid rod, the second rigid rod, and the connecting rod can rotate relative to each other about the third rotation axis. The other rod end of the connecting rod 76 is connected to the sixth hinge 96 such that the third, fourth, and connecting rod can rotate relative to each other about the sixth rotation axis. The rigid connecting rod 76 is connected between the first rod portion 72 and the second rod portion 74, and the first rod portion 72 and the second rod portion 74 move synchronously, thereby achieving parallel movement of the first passive radiator 20 and the second passive radiator 22 along the axial direction.

[0077] As Figure 10 and Figure 11 shown, the horizontal mechanism includes only a single link-bar device. In this case, each of the first through sixth hinges 82, 84, 86, 92, 94, 96 extends along its respective axis of rotation over approximately the entire length of the first and second moving mass blocks 30, 36. In Figure 12 and Figure 13 the sixth embodiment shown, the horizontal mechanism of the connection structure 24 includes a plurality of hinge-bar devices 240, e.g., four hinge-bar devices arranged along the outer edges of the first and second moving masses 30, 36, and Figure 12 and Figure 13 each hinge-bar device 240 of Figure 10 and Figure 11 is the same as that of Figure 12 and Figure 13 (e.g., hinge, bar), except for the length of the hinge. In this case, Figure 10 and Figure 11 the lengths of the respective hinges are shorter than those of the respective hinges of

[0078] In some other embodiments not described, the rod structure may include at least one hinge-bar device disclosed herein. In summary, embodiments of the present invention provide a passive radiator unit and a speaker system using the passive radiator unit. The passive radiator unit includes a connection structure that connects two passive radiators, and the connection structure allows the radiator diaphragm to vibrate normally while preventing harmful rocking motion. The connection structure can be implemented in many different ways. For example, the connection structure may include a flexible member located between the first moving mass block and the second moving mass block, a first connection member connecting the flexible member to the first moving mass block, and a second connection member connecting the flexible member to the second moving mass block. The flexible member may be a corrugated flexible plate or a thin plate provided with cutouts. The central portion of the flexible member may be further supported at a fixed point outside the edge of the radiator, such that the connection structure is very effective for both the asymmetric rocking mode and the symmetric rocking mode of the radiator. The connection structure may also be a rod structure that ensures parallel movement of the first passive radiator and the second passive radiator in the axial direction of the passive radiator unit.

[0079] The embodiments described above and shown in the figures are presented by way of example only and are not intended to limit the concepts and principles of the present invention. Therefore, it should be understood that variations and modifications to the elements and their configurations within the concept or scope of one or more aspects of the present invention fall within the scope of protection of the present invention.

Claims

1. A passive radiator unit, comprising: A first passive radiator including a first moving mass; A second passive radiator opposite to the first passive radiator and including a second moving mass; A connection structure connected between the first moving mass of the first passive radiator and the second moving mass of the second passive radiator, the connection structure being configured to have a radial stiffness greater than its axial stiffness so as to prevent rocking motion while allowing the first passive radiator and the second passive radiator to vibrate axially normally, wherein the connection structure includes: A flexible member located between the first moving mass and the second moving mass; A first connection member connecting the flexible member and the first moving mass; A second connection member connecting the flexible member and the second moving mass; The flexible member has a center and an outer edge, the first connection member is connected to the center of the flexible member, the second connection member is connected to the outer edge of the flexible member, and the flexible member includes one of the following two: a flexible plate having circumferential corrugations arranged radially from the center to the outer edge and a thin plate provided with a cut between the center and the outer edge.

2. The passive radiator unit according to claim 1, wherein the first connection member is a connecting rod or a connecting tube, and the second connection member is a connecting ring.

3. The passive radiator unit according to claim 2, wherein the connecting ring is perforated to prevent deformation of the air spring between the flexible member and the second moving mass.

4. The passive radiator unit according to claim 1, wherein the connection structure further includes a spring structure connecting the flexible member to a fixed point outside the edges of the first and second passive radiators, the fixed point being configured to be fixed relative to the housing for mounting the passive radiator unit.

5. The passive radiator unit according to claim 4, wherein the spring structure includes a plurality of leaf springs.

6. The passive radiator unit according to claim 1, wherein the second connection member is connected to a region of the flexible member, the region being located within the outer edge, the outer edge extending to and being supported by the fixed point, the fixed point being configured to be fixed relative to the housing for mounting the passive radiator unit.

7. A loudspeaker system, comprising: A sound-insulating housing including a first wall and a second wall opposite to each other; And A driver and a passive radiator unit mounted on the sound-insulating housing, the passive radiator unit including: A first passive radiator mounted on the first wall and including a first moving mass; A second passive radiator mounted on the second wall and aligned with the first passive radiator; the second passive radiator includes a second moving mass; And A connecting structure is connected between a first moving mass of the first passive radiator and a second moving mass of the second passive radiator. The connecting structure is configured to have a radial stiffness greater than an axial stiffness, so as to prevent rocking motion while allowing the first passive radiator and the second passive radiator to vibrate axially normally. Wherein, the connecting structure includes: A flexible member located between the first moving mass and the second moving mass; A first connecting member connecting the flexible member and the first moving mass; A second connecting member connecting the flexible member and the second moving mass; The flexible member has a center and an outer edge. The first connecting member is connected to the center of the flexible member, the second connecting member is connected to the outer edge of the flexible member, and the flexible member includes one of the following two: a flexible plate having circumferential corrugations arranged radially from the center to the outer edge and a thin plate having a notch provided between the center and the outer edge.

8. The loudspeaker system according to claim 7, wherein the first connecting member is a connecting rod or a connecting pipe, the second connecting member is a connecting ring, and the connecting ring is perforated to prevent deformation of the air spring between the flexible member and the second moving mass.

9. The loudspeaker system according to claim 7, wherein the connecting structure further includes a spring structure connecting the flexible member to a fixed point, and the fixed point is located outside the edge of the second passive radiator and is fixed relative to the sound insulation housing.

10. The loudspeaker system according to claim 7, wherein the second connecting member is connected to a region of the flexible member, the region is located inside the outer edge and is spaced apart from the outer edge, and the outer edge extends to and is supported by the fixed point, and the fixed point is fixed relative to the sound insulation housing.

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