Speaker box

Abstract

The present invention provides a speaker box, which includes a shell, a sound-generating unit and a magnetic circuit coupling valve. The sound-generating unit includes a basin, a vibration system and a magnetic circuit system. The magnetic circuit system includes a secondary magnet. The shell includes a lower cover. The lower cover, the basin and the magnetic circuit system together form a rear cavity. The lower cover includes a plurality of leakage holes. The magnetic circuit coupling valve is accommodated in the rear cavity. The magnetic circuit coupling valve includes a bracket fixed to the basin or a magnetic yoke, a negative stiffness diaphragm fixed to the bracket, and a coil fixed to the side of the negative stiffness diaphragm close to the secondary magnet and spaced from the secondary magnet. The negative stiffness diaphragm is opposite to the leakage hole and spaced from the secondary magnet. The coil receives an external control signal and generates an electromagnetic field together with the secondary magnet to drive the negative stiffness diaphragm to abut against the leakage hole and seal it in a closed state, or to move away from the leakage hole to make it in an open state, or to partially abut against the leakage hole to make it in a partially open and closed state. Compared with the related art, the speaker box of the present invention can accurately control the connection state between the rear cavity and the outside air and has excellent acoustic performance.

Description

[Technical field]

[0001] The invention relates to the field of acoustics and electricity, and in particular to a speaker box used in portable electronic products. [Background technology]

[0002] With the advent of the mobile Internet era, the number of smart mobile devices continues to rise. Among the many mobile devices, mobile phones are undoubtedly the most common and portable mobile terminal devices. Speaker boxes used to play sound are widely used in smart mobile devices such as mobile phones. The volume of the back cavity used in the speaker box is directly related to the sound quality of the speaker box.

[0003] Related technology: The vibration system of a speaker box includes a shell and a sound-emitting unit. The sound-emitting unit divides the shell into a front cavity and a rear cavity. In order to achieve air pressure balance and heat dissipation in the rear cavity, the shell is provided with a vent hole connecting the rear cavity with the outside world, and a valve is provided on the vent hole to control the connection between the rear cavity and the outside world.

[0004] However, in the speaker box of the related art, the valve and the switch component that controls the valve switch have not been disclosed in specific device form, and the control capability, response speed and stability of the valve switch have not been resolved and reflected in the solution. Furthermore, the technical solution of the related art mainly solves the air pressure regulation in the back cavity, and does not propose a solution for sound leakage control, thereby limiting the acoustic performance of the speaker box. How to make the speaker box vibrate to form an ideal acoustic dipole when the sound-emitting surface vibrates, optimize sound leakage control when used as a receiver in call mode, and improve sound isolation, so that the acoustic performance of the speaker box is improved is a technical problem that needs to be solved.

[0005] Therefore, it is necessary to provide a new speaker box to solve the above technical problems. [Summary of the invention]

[0006] The object of the present invention is to provide a speaker box which can accurately control the connection between the back cavity and the outside and has excellent acoustic performance.

[0007] In order to achieve the above-mentioned object, the present invention provides a speaker box, which includes a shell and a sound-emitting unit fixedly accommodated in the shell, the sound-emitting unit includes a basin frame and a vibration system and a magnetic circuit system with a magnetic gap respectively fixed to the basin frame, the magnetic circuit system includes a yoke, a main magnetic steel fixed to the yoke, and a secondary magnetic steel spaced from the main magnetic steel to form the magnetic gap, the shell includes a lower cover fixed to the basin frame, the lower cover, the basin frame and the magnetic circuit system together form a rear cavity, the lower cover includes one or more leakage holes running through it, and the rear cavity is connected to the outside through the leakage holes; the speaker The box also includes a magnetic circuit coupling valve accommodated in the rear cavity, and the magnetic circuit coupling valve includes a bracket fixed to the basin frame or the magnetic yoke, a negative stiffness diaphragm fixed to the bracket, and a coil fixed to the negative stiffness diaphragm close to the side of the secondary magnet and spaced from the secondary magnet, the negative stiffness diaphragm is opposite to the leakage hole and is spaced apart; the coil receives an external control signal and generates an electromagnetic field together with the secondary magnet to drive the negative stiffness diaphragm to abut against the leakage hole and seal it in a closed state, or to move away from the leakage hole to make it in an open state, or to partially abut against the leakage hole to make it in a partially open and closed state.

[0008] Preferably, the auxiliary magnets include two and are respectively arranged on opposite sides of the main magnet, the lower cover includes a lower cover plate arranged opposite to the yoke and spaced apart from each other, and a lower cover side wall extending from the periphery of the lower cover plate along the outer side of the sound unit and fixedly connected to the basin frame; the leakage hole is located on the side wall of the lower cover, and the magnetic circuit coupling valve is arranged on a side of one of the auxiliary magnets away from the main magnet.

[0009] Preferably, the negative stiffness diaphragm includes a seal and an elastic film for sealing the leakage hole, and the seal is arranged opposite to the leakage hole; the elastic film includes a first fixed portion, an elastic bent portion extended by bending from the outer periphery of the first fixed portion, and a second fixed portion extending from a side of the elastic bent portion away from the first fixed portion and fixed to a side of the bracket away from the secondary magnet; the coil is fixed to a side of the first fixed portion close to the secondary magnet, and the seal is fixed to a side of the first fixed portion away from the secondary magnet; when the coil is not energized, a distance between the second fixed portion and the seal along a moving direction of the coil is greater than a distance between the second fixed portion and a side wall of the lower cover on a side where the leakage hole is provided along the moving direction of the coil.

[0010] Preferably, the negative stiffness diaphragm is a symmetrical structure or an asymmetrical structure.

[0011] Preferably, the negative stiffness diaphragm is in the shape of a rectangle with bilateral symmetry or four-sided symmetry, or a rectangle with four asymmetric corners, or one side is hinged and fixed, and the other side is in a negative stiffness bent shape.

[0012] Preferably, the magnetic circuit system further comprises a secondary magnetic conductive plate fixed to a side of the secondary magnetic steel away from the magnetic yoke, the coil is in a runway shape, and the secondary magnetic conductive plate at least partially extends into the coil.

[0013] Preferably, the speaker box further comprises a gasket accommodated in the rear cavity, and the gasket is fixed to the inner side of the side wall of the lower cover provided with the leakage hole.

[0014] Preferably, the gasket is a rubber sheet, a flexible foam, a polymer gel or a high-viscosity grease.

[0015] Preferably, the vibration system includes a diaphragm fixed to the basin frame and a voice coil fixed to the diaphragm and inserted in the magnetic gap to drive the diaphragm to vibrate and produce sound; the sound-emitting unit also includes an upper cover, which is pressed on the diaphragm and together with the diaphragm forms a front cavity, the upper cover is provided with a sound hole, and the front cavity is connected to the outside world through the sound hole.

[0016] Preferably, the vibration system also includes an elastic support component fixed to the basin frame and connected to the end of the voice coil away from the diaphragm; the elastic support component is provided with four soldering pads, and the four soldering pads are respectively located at the four corners of the elastic support component; the two leads of the voice coil are welded to two of the soldering pads; the two leads of the coil are welded to the other two soldering pads, or one lead of the coil is welded to one of the two soldering pads to realize sharing a soldering pad as a negative electrode with the voice coil.

[0017] Compared with the related art, the speaker box of the present invention is provided with a magnetic circuit coupling valve in the rear cavity, and the magnetic circuit coupling valve includes a bracket, a coil and a negative stiffness diaphragm, and the lower cover of the shell is provided with a plurality of leakage holes. Among them, the bracket is fixed to the basin frame or the magnetic yoke, the negative stiffness diaphragm is fixed to the bracket, the coil is fixed to the side of the negative stiffness diaphragm close to the secondary magnetic steel and spaced from the secondary magnetic steel, and the negative stiffness diaphragm is directly opposite to the leakage hole and spaced. This structure enables the coil to receive an external control signal and generate an electromagnetic field together with the secondary magnetic steel when the negative stiffness diaphragm is working, so as to drive the negative stiffness diaphragm to abut against the leakage hole and seal it in a closed state, or to move away from the leakage hole to make it in an open state, or to partially abut against the leakage hole to make it in a partially open and closed state. Specifically, the negative stiffness diaphragm can seal the leakage hole, and the use of the negative stiffness diaphragm can optimize the sound leakage control and improve the sound isolation, thereby improving the acoustic performance of the speaker box. On the other hand, the above structure enables the connection between the rear cavity and the outside world to be achieved by the magnetic circuit coupling valve to accurately control the leakage hole. The opening or closing action of the magnetic circuit coupling valve only requires a single short-term external linear voltage input control signal to achieve a bistable state of stable opening and closing. When the magnetic circuit coupling valve controls the partial opening and closing state of the leakage hole, it only needs to continuously input a small short-term external linear voltage input control signal to achieve precise control. The signal is determined by the stiffness coefficient of the negative stiffness diaphragm and the driving force of the coil, so that the speaker box can accurately control the connection state between the rear cavity and the outside air and has excellent acoustic performance.

Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work, among which:

[0019] Figure 1 It is a schematic diagram of the three-dimensional structure of the speaker box of the present invention;

[0020] Figure 2 It is a partial exploded view of the three-dimensional structure of the speaker box of the present invention;

[0021] Figure 3 For along Figure 1 The cross-section diagram of the AA line;

[0022] Figure 4 It is an assembly diagram of the sound-generating monomer and the magnetic circuit coupling valve structure in the embodiment of the speaker box of the present invention;

[0023] Figure 5 It is an assembly diagram of the sound-generating monomer and the magnetic circuit coupling valve structure in another embodiment of the speaker box of the present invention;

[0024] Figure 6 It is a three-dimensional structural schematic diagram of a magnetic circuit coupling valve of a speaker box of the present invention;

[0025] Figure 7 for Figure 6 Schematic diagram of the partial decomposition structure;

[0026] Figure 8 It is a schematic diagram of the working principle structure of the magnetic circuit coupling valve of the speaker box of the present invention;

[0027] Fig. 9 for Figure 8 Schematic diagram of the displacement-time relationship of the negative stiffness diaphragm;

[0028] Fig.10 for Figure 8 Schematic diagram of the force-time relationship of the negative stiffness diaphragm;

[0029] Fig.11 for Figure 8 Schematic diagram of the structure of a method for achieving inward buckling of a negative stiffness diaphragm. [Specific implementation method]

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] Please refer to Figure 1-4 As shown, the present invention provides a speaker box 100, which includes a sound unit 10, a shell 20 and a magnetic circuit coupling valve 4.

[0032] The sound-generating unit 10 is fixedly accommodated in the housing 20. Specifically, the sound-generating unit 10 includes a basin frame 1, a vibration system 2 fixed to the basin frame 1, and a magnetic circuit system 3 having a magnetic gap 30.

[0033] The vibration system 2 includes a diaphragm 21 , a voice coil 22 and an elastic supporting component 23 .

[0034] The diaphragm 21 is fixed to the basin frame 1 .

[0035] The voice coil 22 is fixed to the diaphragm 21. The voice coil 22 is inserted into the magnetic gap 30 to drive the diaphragm 21 to vibrate and generate sound.

[0036] The elastic support component 23 is fixed to the basin frame 1 and connected to the end of the voice coil 22 away from the diaphragm 21. Specifically, the elastic support component 23 includes an elastic member 231 fixed to the basin frame 1 at one end and fixed to the end of the voice coil 22 away from the diaphragm 21 at the other end, and an auxiliary diaphragm 232 connected to the side of the elastic member 231 away from the diaphragm 21. On the one hand, it is used to strengthen the vibration effect of the diaphragm 21 and improve the acoustic performance of the speaker box 100, and on the other hand, it is used to balance the swing of the vibration system 2 and improve the stability of the speaker box 100.

[0037] Preferably, the elastic member 231 is a flexible circuit board, and the voice coil 22 is electrically connected to the elastic member 231. On the one hand, it is used to improve the vibration strength and balance of the vibration system 2 and suppress swaying. On the other hand, the voice coil 22 is connected to an external power supply, avoiding the risk of the voice coil lead wire being easily broken when the voice coil lead wire structure leads out the power supply.

[0038] The magnetic circuit system 3 is used to drive the vibration system 2 to vibrate and generate sound. Specifically, the magnetic circuit system 3 includes a yoke 31, a main magnetic steel 32 fixed to the yoke 31, a secondary magnetic steel 33 spaced apart from the main magnetic steel 32 to form the magnetic gap 30, and a secondary magnetic conductive plate 34 fixed to the side of the secondary magnetic steel 33 away from the yoke 31.

[0039] In this embodiment, the yoke 31 is fixed to the basin frame 1 .

[0040] In this embodiment, the main magnetic steel 32 is rectangular. The auxiliary magnetic steel 33 includes two, and the two auxiliary magnetic steels 33 are respectively located on opposite sides of the main magnetic steel 32. Specifically, the two auxiliary magnetic steels 33 are respectively located on opposite sides of the long axis of the main magnetic steel 32. The elastic support components 23 include two and are respectively located on opposite sides of the short axis of the main magnetic steel 32.

[0041] The housing 20 includes an upper cover 203 and a lower cover 201 .

[0042] The upper cover 203 is pressed on the diaphragm 21. The upper cover 203 and the diaphragm 21 together form a front cavity 204. The front cavity 204 is used to improve the high-frequency acoustic performance of the speaker box 100. The upper cover 203 is provided with a sound hole 2030. The front cavity 204 is connected to the outside through the sound hole 2030. This structure enables the front cavity 204 to form a front sound-emitting structure for high-frequency sound through the sound hole 2030.

[0043] The lower cover 201 is fixed to the basin frame 1. The lower cover 201, the basin frame 1 and the magnetic circuit system 3 together form a rear cavity 202. The rear cavity 202 is used to improve the low-frequency acoustic performance of the speaker box 100.

[0044] Specifically, the lower cover 201 includes a lower cover plate 2011 spaced apart from the yoke 31, a lower cover side wall 2012 extending from the periphery of the lower cover plate 2011 along the outer side of the sound-emitting unit 10 and fixedly connected to the basin frame 1, and one or more leakage holes 2010 passing therethrough. The rear cavity 202 is connected to the outside through the leakage holes 2010.

[0045] The plurality of leakage holes 2010 may be thin-walled holes in the form of an array of square, circular, etc. In this embodiment, the total area of ​​the plurality of leakage holes 2010 is the same as or similar to the area of ​​the sound holes 2030. This structure makes the area of ​​the plurality of leakage holes 2010 similar to the area of ​​the earpiece as a receiver. In this embodiment, the total area of ​​the plurality of leakage holes 2010 is set to be the same as the area of ​​the sound holes 2030, so that the acoustic performance of the speaker box 100 is good.

[0046] In this embodiment, the leakage hole 2010 is set through the lower cover side wall 2012. That is, the leakage hole is located on the lower cover side wall. This structure enables the rear cavity 202 to form a side sound-emitting structure for low-frequency sound through the leakage hole 2010.

[0047] The magnetic circuit coupling valve 4 is accommodated in the rear cavity 202. In the present embodiment, the magnetic circuit coupling valve 4 is disposed on a side of one of the auxiliary magnetic steels 33 away from the main magnetic steel 32.

[0048] Specifically, the magnetic circuit coupling valve 4 includes a bracket 43, a negative stiffness diaphragm 42 and a coil 41. The bracket 43 is fixed to the basin frame 1 or the magnetic yoke 31. The bracket 43 is assembled with the sound unit 10 and then assembled to the speaker box 100. In this embodiment, the bracket 43 is fixed to the basin frame 1.

[0049] The negative stiffness diaphragm 42 is fixed to the bracket 43. The negative stiffness diaphragm 42 is directly opposite to the leakage hole 2010 and is spaced apart from each other.

[0050] The coil 41 is fixed to a side of the negative stiffness diaphragm 42 close to the secondary magnetic steel 33 and is spaced apart from the secondary magnetic steel 33 .

[0051] In this embodiment, the coil 41 is in a racetrack shape. The secondary magnetic conductive plate 34 at least partially extends into the coil 41. This structure increases the magnetic circuit performance of the magnetic circuit coupling valve 4.

[0052] The magnetic circuit coupling valve 4 utilizes the auxiliary magnetic steel 33 of the magnetic circuit system 3 as the driving magnetic field, and utilizes the coil 41 to drive the negative stiffness diaphragm 42 to realize the opening and closing control of the leakage hole 2010. Of course, it is not limited to this, please refer to Figure 5 As shown, in another embodiment, the magnetic circuit coupling valve 4a is arranged on the same side of the yoke 31a, the coil 41a is stacked on the auxiliary magnetic steel 33a, and the negative stiffness diaphragm 42a is on the same side of the yoke 31a.

[0053] The coil 41 receives an external control signal and generates an electromagnetic field with the secondary magnet 33 to drive the negative stiffness diaphragm 42 to abut against the leakage hole 2010 and seal it in a closed state, or to move away from the leakage hole 2010 to make it open, or to partially abut against the leakage hole 2010 to make it partially open and closed. The working principle of the magnetic circuit coupling valve 4 is the same as that of the sound-emitting unit 10. Specifically, the coil 41 generates an electromagnetic field with the secondary magnet 33 after being energized, and the coil 41 is subjected to the Lorentz force. By changing the positive and negative phases of the current of the coil 41, the force direction of the coil 41 is also changed, so that it can be close to the leakage hole 2010 or away from the leakage hole 2010. The negative stiffness diaphragm 42 can seal the leakage hole 2010. The use of the negative stiffness diaphragm 42 can optimize the sound leakage control and improve the sound isolation, thereby improving the acoustic performance of the speaker box 100. The above structure enables the connection between the rear cavity 202 and the outside world to be realized by the magnetic circuit coupling valve 42 to precisely control the leakage hole 2010. The opening or closing action of the magnetic circuit coupling valve 42 only requires a single short-term loading of an external linear voltage input control signal to achieve a bistable state of stable opening and closing. The bistable magnetic circuit coupling valve 42 can save energy consumption of the speaker box 100 and has stable performance. The negative stiffness diaphragm 42 is a polymer film, and the speaker box 100 uses electromagnetic excitation and polymer film to realize the motion structure to improve reliability. More preferably, when the magnetic circuit coupling valve 42 controls the partial opening and closing state of the leakage hole 2010, it is only necessary to continuously input a small short-time loading external linear voltage input control signal to achieve precise control. The signal is determined by the stiffness coefficient of the negative stiffness diaphragm 42 and the driving force of the coil 41. The size of the leakage hole 2010 is controlled with high precision through the size of the external linear voltage, thereby realizing intelligent speaker rear cavity control, thereby providing more sound modes and better bass effects, so that the speaker box 100 can accurately control the connectivity between the rear cavity 202 and the outside air and has excellent acoustic performance.

[0054] Please also refer to Figure 6-7 As shown, the negative stiffness diaphragm 42 includes a sealing member 421 and an elastic membrane 422 for sealing the leakage hole 2010 .

[0055] The sealing member 421 is arranged opposite to the leakage hole 2010. The pre-pressure design of the sealing member 421 ensures that the rear cavity 202 of the speaker box 100 will not change its closed state under an air pressure of more than 5000 Pa.

[0056] The elastic film 422 includes a first fixing portion 4223, an elastic bending portion extending from the outer periphery of the first fixing portion 4223, and a second fixing portion 4221 extending from a side of the elastic bending portion away from the first fixing portion 4223 and fixed to a side of the bracket 43 away from the secondary magnet. The coil 41 is fixed to a side of the first fixing portion 4223 close to the secondary magnet 33. The seal 421 is fixed to a side of the first fixing portion 4223 away from the secondary magnet 33.

[0057] The first fixing portion 4223 fixed to the bracket 43 away from the secondary magnetic steel 33, the elastic bending portion 4222 bent and extended from the first fixing portion 4223, and the second fixing portion 4221 extended from the elastic bending portion 4222 and fixed to the sealing member 421. When the rear cavity 202 is connected to the outside through the leakage hole 2010.

[0058] When the coil 41 is not energized, the distance between the second fixing portion 4221 and the sealing member 421 along the moving direction of the coil 41 is greater than the distance between the second fixing portion 4221 and the lower cover side wall 2012 on the side where the leakage hole 2010 is provided along the moving direction of the coil 41. Figure 8 As shown, the seal 421 in the negative stiffness diaphragm 42 is supported by the elastic membrane 422 and pressed against the lower cover side wall 2012. The distance between the position b of the second fixing portion 4221 and the position c of the first fixing portion 4223 (the position c is the position of the negative stiffness diaphragm 42 when it is not sealed) is greater than the distance between the position b of the second fixing portion 4221 and the position c' of the first fixing portion 4223 (the position c' is the position of the negative stiffness diaphragm 42 when it is not sealed). This setting enables the negative stiffness of the negative stiffness diaphragm 42 to generate negative stiffness, thereby achieving sealing between the seal 421 and the lower cover side wall 2012. Please also refer to Figure 9-10 , the displacement of the first fixing portion 4223 from position c to c' and the elastic reaction force of the lower cover side wall 2012 are Figure 9-10 It can be seen that after 1.6 seconds, the stiffness and displacement are both negative and are called the negative stiffness interval.

[0059] In the present embodiment, one of the methods for realizing the negative stiffness diaphragm 42 is pre-extension of the film. The pre-extension of the film is obtained by superimposing a certain pre-pressure on the elastic amplitude according to the dimension h1 from position b to position d of the lower cover side wall 2012, and obtaining the distance h2 from position b to position c. Then, the curvature integral is used to obtain the length of the diaphragms on both sides.

[0060] Another method of realizing the negative stiffness diaphragm 42 is to buckle the film inward. Fig.11 The film buckling generates prestress by squeezing the two sides of the U-shaped elastic film 422 toward the middle to achieve negative stiffness. First, a flat piece is obtained by punching, and when assembling, the elastic film 422 is limited at position i, position j, and position k to achieve prestress.

[0061] In this embodiment, the negative stiffness diaphragm 42 is a symmetrical structure or an asymmetrical structure. Among them, for the corresponding symmetrical structure, the negative stiffness diaphragm 42 is a rectangle with bilateral symmetry or four-sided symmetry. For the asymmetrical structure, the negative stiffness diaphragm 42 can be a rectangle with four asymmetrical corners, or one side is hinged and fixed and the other side is in a negative stiffness bending shape, or the seal 421 is triangular. When the three sides of the seal 421 are in a triangular shape, a negative stiffness membrane with a hinge structure is formed, wherein the base of the triangle serves as a pre-stress membrane and the vertex of the triangle serves as a hinge membrane.

[0062] In this embodiment, the elastic support component 23 is provided with four pads 230. The four pads 230 are respectively located at the four corners of the elastic support component 23. Specifically, the pads 230 are located at the elastic member 231. The elastic member 231 is electrically connected to the voice coil 22 and the coil 41, respectively. The two leads of the voice coil 22 are welded to two of the pads 230. The two leads of the coil 41 are welded to the other two pads 230, or one lead of the coil 41 is welded to one of the two pads 230 to realize sharing one pad 230 as the negative pole with the voice coil 22. This structure allows the leads of the coil 41 to independently use the two idle pads 230 in the elastic support component 23, or use the same pad 230 as the negative pole, thereby making the circuit connection structure of the speaker box 100 simple and easy to connect.

[0063] In this embodiment, in order to better increase the sealing performance of the negative stiffness diaphragm 42. The speaker box 100 also includes a gasket 5 accommodated in the rear cavity 202. The gasket 5 improves the airtightness between the negative stiffness diaphragm 42 and the lower cover side wall 2012. The gasket 5 is fixed to the inner side of the lower cover side wall 2012 provided with the leakage hole 2010. In order to better increase the sealing performance of the negative stiffness diaphragm 42, the shape of the gasket 5 matches the lower cover side wall 2012. The gasket 5 is any one of a rubber sheet, a flexible foam with an adhesive layer, a polymer gel, and a high-viscosity grease.

[0064] Compared with the related art, the speaker box of the present invention is provided with a magnetic circuit coupling valve in the rear cavity, and the magnetic circuit coupling valve includes a bracket, a coil and a negative stiffness diaphragm, and the lower cover of the shell is provided with a plurality of leakage holes. Among them, the bracket is fixed to the basin frame or the magnetic yoke, the negative stiffness diaphragm is fixed to the bracket, the coil is fixed to the side of the negative stiffness diaphragm close to the secondary magnetic steel and spaced from the secondary magnetic steel, and the negative stiffness diaphragm is directly opposite to the leakage hole and spaced. This structure enables the coil to receive an external control signal and generate an electromagnetic field together with the secondary magnetic steel when the negative stiffness diaphragm is working, so as to drive the negative stiffness diaphragm to abut against the leakage hole and seal it in a closed state, or to move away from the leakage hole to make it in an open state, or to partially abut against the leakage hole to make it in a partially open and closed state. Specifically, the negative stiffness diaphragm can seal the leakage hole, and the use of the negative stiffness diaphragm can optimize the sound leakage control and improve the sound isolation, thereby improving the acoustic performance of the speaker box. On the other hand, the above structure enables the connection between the rear cavity and the outside world to be achieved by the magnetic circuit coupling valve to accurately control the leakage hole. The opening or closing action of the magnetic circuit coupling valve only requires a single short-term external linear voltage input control signal to achieve a bistable state of stable opening and closing. When the magnetic circuit coupling valve controls the partial opening and closing state of the leakage hole, it only needs to continuously input a small short-term external linear voltage input control signal to achieve precise control. The signal is determined by the stiffness coefficient of the negative stiffness diaphragm and the driving force of the coil, so that the speaker box can accurately control the connection state between the rear cavity and the outside air and has excellent acoustic performance.

[0065] The above description is only an implementation mode of the present invention. It should be pointed out that, for ordinary technicians in this field, improvements can be made without departing from the creative concept of the present invention, but these all belong to the protection scope of the present invention.

Claims

1. A speaker box, comprising a shell and a sound-generating unit fixedly accommodated in the shell, wherein the sound-generating unit comprises a basin frame and a vibration system respectively fixed to the basin frame and a magnetic circuit system having a magnetic gap, wherein the magnetic circuit system comprises a yoke, a main magnetic steel fixed to the yoke, and a secondary magnetic steel spaced from the main magnetic steel to form the magnetic gap, characterized in that: The housing includes a lower cover fixed to the basin frame, the lower cover, the basin frame and the magnetic circuit system together enclose a rear cavity, the lower cover includes one or more leakage holes penetrating therethrough, and the rear cavity is connected to the outside through the leakage holes; The speaker box also includes a magnetic circuit coupling valve accommodated in the rear cavity, and the magnetic circuit coupling valve includes a bracket fixed to the basin frame or the magnetic yoke, a negative stiffness diaphragm fixed to the bracket, and a coil fixed to the negative stiffness diaphragm on the side close to the secondary magnet and spaced from the secondary magnet, the negative stiffness diaphragm is opposite to the leakage hole and is spaced apart; the coil receives an external control signal and generates an electromagnetic field together with the secondary magnet to drive the negative stiffness diaphragm to abut against the leakage hole and seal it in a closed state, or to move away from the leakage hole to make it in an open state, or to partially abut against the leakage hole to make it in a partially open and closed state.

2. The speaker box according to claim 1, characterized in that: The auxiliary magnets include two and are respectively arranged on opposite sides of the main magnet, the lower cover includes a lower cover plate arranged opposite to the magnetic yoke and a lower cover side wall extending from the periphery of the lower cover plate along the outer side of the sound unit and fixedly connected to the basin frame; the leakage hole is located on the side wall of the lower cover, and the magnetic circuit coupling valve is arranged on a side of one of the auxiliary magnets away from the main magnet.

3. The speaker box according to claim 2, characterized in that: The negative stiffness diaphragm includes a sealing member and an elastic film for sealing the leakage hole, and the sealing member is arranged opposite to the leakage hole; the elastic film includes a first fixed portion, an elastic bent portion extending from the outer periphery of the first fixed portion, and a second fixed portion extending from a side of the elastic bent portion away from the first fixed portion and fixed to a side of the bracket away from the secondary magnet; the coil is fixed to a side of the first fixed portion close to the secondary magnet, and the sealing member is fixed to a side of the first fixed portion away from the secondary magnet; when the coil is not energized, the distance between the second fixed portion and the sealing member along the moving direction of the coil is greater than the distance between the second fixed portion and the side wall of the lower cover on the side where the leakage hole is provided along the moving direction of the coil.

4. The speaker box according to claim 3, characterized in that: The negative stiffness diaphragm has a symmetrical structure or an asymmetrical structure.

5. The speaker box according to claim 4, characterized in that: The negative stiffness diaphragm is in a bilaterally symmetrical or four-sided symmetrical rectangle, or a rectangle with four asymmetrical corners, or one side is hinged and fixed, and the other side is in a negative stiffness bending shape.

6. The speaker box according to claim 2, characterized in that: The magnetic circuit system further comprises a secondary magnetic conductive plate fixed to a side of the secondary magnetic steel away from the magnetic yoke, the coil is in a runway shape, and the secondary magnetic conductive plate at least partially extends into the coil.

7. The speaker box according to claim 2, characterized in that: The speaker box further comprises a gasket accommodated in the rear cavity, and the gasket is fixed to the inner side of the side wall of the lower cover provided with the leakage hole.

8. The speaker box according to claim 7, characterized in that: The gasket is a rubber sheet, flexible foam, polymer gel or high-viscosity grease.

9. The speaker box according to claim 1, characterized in that: The vibration system includes a diaphragm fixed to the basin frame and a voice coil fixed to the diaphragm and inserted in the magnetic gap to drive the diaphragm to vibrate and produce sound; the sound-emitting unit also includes an upper cover, which is pressed on the diaphragm and together with the diaphragm forms a front cavity, the upper cover is provided with a sound hole, and the front cavity is connected to the outside world through the sound hole.

10. The speaker box according to claim 9, characterized in that: The vibration system also includes an elastic support component fixed to the basin frame and connected to the end of the voice coil away from the diaphragm; the elastic support component is provided with four soldering pads, and the four soldering pads are respectively located at the four corners of the elastic support component; the two leads of the voice coil are welded to two of the soldering pads; the two leads of the coil are welded to the other two soldering pads, or one lead of the coil is welded to one of the two soldering pads to realize sharing a soldering pad as a negative electrode with the voice coil.

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