A micro speaker and a speaker assembly thereof

Abstract

The present application relates to acoustic equipment technology, and discloses a micro loudspeaker, which comprises a loudspeaker assembly and a sound absorption assembly.The loudspeaker assembly comprises a diaphragm and a paper tube, and the paper tube is provided with a second ball groove at the end thereof.The sound absorption assembly comprises a fixed cavity and an induction unit, and the induction unit is used for increasing the sound absorption coefficient at low frequency and suppressing the sound absorption coefficient at high frequency.At low frequency, the current of the induction coil is increased, the magnetic field intensity of the induction coil is increased, the viscosity of the magneto-rheological fluid is increased, and the sound absorption coefficient is increased.At high frequency, the current of the induction coil is reduced, the magnetic field intensity of the induction coil is reduced, the viscosity of the magneto-rheological fluid is reduced, the sound absorption coefficient is reduced, and the sound absorption requirement of the target frequency band is accurately matched.The present application further discloses a loudspeaker assembly which is composed of one or more micro loudspeakers.

Description

Technical Field

[0001] This invention relates to audio equipment technology, and more particularly to a miniature loudspeaker and its loudspeaker assembly. Background Technology

[0002] Loudspeakers convert electrical signals into mechanical vibrations through electromagnetic induction, thereby generating sound waves. Because bass sound waves have a longer wavelength, they may interfere with external low-frequency noise in a larger space, causing certain frequencies of sound to be amplified or weakened.

[0003] In loudspeaker noise control technology, active-passive composite sound absorption technology, by combining passive sound-absorbing materials with active acoustic control systems, demonstrates significant advantages in broadening the low-frequency sound absorption bandwidth. However, existing technologies still have many limitations. Traditional active-passive series composite sound absorption structures are bulky due to the stacked design of passive material layers and active control units, making them difficult to meet the application requirements of compact spaces; semi-active sound absorption and active impedance control methods require high-precision modeling and real-time identification of the mechanical parameters of each loudspeaker, such as diaphragm displacement characteristics, and electrical parameters.

[0004] The displacement prediction model correction requirement mentioned in Chinese patent application CN114390406A significantly increases system complexity and implementation cost; in addition, traditional active sound absorption systems require a large number of loudspeaker units to achieve large-area sound field control, which further restricts their engineering applicability.

[0005] To address the aforementioned issues, while existing technologies optimize speaker performance through dynamic control of diaphragm displacement, and Chinese patent application CN114390406A improves displacement prediction accuracy through adjustment of correction coefficients, the core contradiction between the volume and cost of sound-absorbing structures remains unresolved. In particular, the coupling design between the active unit and the passive layer in traditional series structures easily leads to acoustic impedance mismatch, limiting low-frequency sound absorption efficiency, and the multi-unit layout exacerbates system complexity. Therefore, a novel active-passive composite sound-absorbing configuration is urgently needed that can overcome the bottleneck in low-frequency sound absorption performance while achieving compact and low-cost deployment.

[0006] Furthermore, in existing sound field control theories, the influence of higher-order sound fields on sound absorption performance is often simplified, and the layout of error microphones lacks a systematic optimization basis, resulting in insufficient sound absorption frequency band stability in practical applications. How to maximize broadband sound absorption performance within a limited volume through accurate sound field modeling and impedance matching design remains a difficult technical challenge in this field. Summary of the Invention

[0007] Based on the above-mentioned technical problems, the present invention proposes a miniature loudspeaker and its loudspeaker assembly.

[0008] The technical solution of this invention is implemented as follows:

[0009] A miniature loudspeaker, characterized in that it comprises:

[0010] A speaker assembly, comprising a diaphragm and a paper tube, wherein a second ball groove is provided at the end of the paper tube;

[0011] The sound-absorbing component includes a fixed cavity and a sensing unit, wherein the sensing unit increases the sound absorption coefficient at low frequencies and suppresses the sound absorption coefficient at high frequencies.

[0012] The space between the fixed cavity and the sensing unit is filled with a porous sound-absorbing material. The sensing unit includes a stator disk, which includes a main frame. The main frame has multiple receiving cavities, and the outer side of each receiving cavity is covered with a flexible material.

[0013] The stator disk has multiple iron cores evenly spaced along its inner diameter, with induction coils wound around the iron cores. A permanent magnet turntable is located in the center of the stator disk, and a first ball groove is located in the center of the permanent magnet turntable.

[0014] The second ball groove is disposed through the middle of the permanent magnet turntable and cooperates with the first ball groove. When the paper tube vibrates, the first ball groove and the second ball groove drive the permanent magnet turntable to rotate.

[0015] In this invention, the induction coil consists of a first coil and a second coil connected in series. The second coil is located inside a accommodating cavity, which is filled with magnetorheological fluid.

[0016] In this invention, the current generated by the induction coil at low frequencies is greater than that at high frequencies.

[0017] in,

[0018] At low frequencies, the current in the induction coil increases, the magnetic field strength of the induction coil increases, the viscosity of the magnetorheological fluid increases, and the sound absorption coefficient increases.

[0019] At high frequencies, the current in the induction coil decreases, the magnetic field strength of the induction coil decreases, the viscosity of the magnetorheological fluid decreases, and the sound absorption coefficient decreases.

[0020] In this invention, the displacement amplitude of the diaphragm at low frequency is greater than that at high frequency, wherein the rotation frequency of the permanent magnet turntable driven by the paper tube, the first ball groove and the second ball groove at low frequency is greater than that at high frequency.

[0021] In this invention, the speaker assembly further includes a sound-amplifying disk, which has multiple sound-absorbing cavities arranged circumferentially, and multiple sound-guiding holes arranged below the sound-absorbing cavities. A sound-absorbing assembly is installed below the sound-guiding holes.

[0022] In this invention, the flexible material is connected to the fixed cavity and the sensing unit by filling with a porous sound-absorbing material.

[0023] In this invention, the permanent magnet turntable is composed of a first permanent magnet disk and a second permanent magnet disk, with the teeth of the first permanent magnet disk and the second permanent magnet disk being distributed alternately.

[0024] In this invention, the speaker assembly consists of a sound amplification coil and a base. The base includes a permanent magnet, and a hole is provided in the middle of the permanent magnet. A first iron plate and a second iron plate are provided on the upper and lower surfaces of the permanent magnet, wherein a cylindrical boss is provided in the middle of the second iron plate.

[0025] In this invention, the amplifying coil includes an amplifying disk, the interior of which is provided with a diaphragm, wherein a paper tube is fixedly connected to the middle of the diaphragm, and a copper coil is provided at the lower end of the paper tube.

[0026] A loudspeaker assembly, characterized in that it comprises one or more miniature loudspeakers.

[0027] The miniature loudspeaker and loudspeaker assembly of the present invention have the following beneficial effects:

[0028] This invention precisely matches the sound absorption requirements of the target frequency band. When low-frequency sound waves cause a large displacement of the diaphragm, the high-speed rotation of the permanent magnet disk drives the induction coil to generate a strong current, which significantly increases the viscosity of the magnetorheological fluid, effectively absorbing standing wave energy, eliminating low-frequency sound pressure distortion, and ensuring bass uniformity. Under high-frequency vibration, the diaphragm displacement amplitude decreases, the rotation speed of the permanent magnet disk decreases, and the induced current weakens. At this time, the viscosity of the magnetorheological fluid decreases, the sound absorption coefficient decreases, reducing excessive absorption of high-frequency sound waves, avoiding loss of sound details, and suppressing external high-frequency noise aliasing. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of the speaker assembly of the present invention;

[0030] Figure 2 This is a partial structural schematic diagram of the speaker assembly of the present invention;

[0031] Figure 3 This is a schematic diagram of the structure of the speaker assembly of the present invention;

[0032] Figure 4 This is a schematic diagram of the sound-absorbing component of the present invention;

[0033] Figure 5 This is a schematic diagram of the structure of the sensing unit of the present invention;

[0034] Figure 6 This is a schematic diagram of the sensing unit of the present invention from another angle;

[0035] Figure 7 This is a schematic block diagram of the sensing unit of the present invention;

[0036] The reference numerals in the attached drawings are as follows: 10 for the speaker assembly, 11 for the amplifier coil, 111 for the amplifier disk, 111A for the sound-absorbing cavity, 111B for the sound guide hole, 112 for the diaphragm, 113 for the paper tube, 114 for the copper coil, 115 for the second ball groove, 12 for the base, 121 for the permanent magnet, 122 for the first iron plate, 123 for the second iron plate, 124 for the cylindrical boss, 20 for the sound-absorbing assembly, 21 for the fixed cavity, 21A for the filling cavity, 21B for the guide strip, 22 for the sound guide cavity, 23 for the sound guide tube, 24 for the induction unit, 241 for the stator disk, 241A for the main frame, 241B for the accommodating cavity, 241C for the flexible material, 242 for the iron core, 243 for the induction coil, 243A for the first coil, 243B for the second coil, 244 for the permanent magnet turntable, 244A for the first permanent magnet disk, 244B for the second permanent magnet disk, and 244C for the first ball groove. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Example 1

[0038] Reference Figures 1 to 3 As shown, this embodiment discloses a miniature loudspeaker including a sound-emitting component 10 and a sound-absorbing component 20. The sound-absorbing component 20 is used to adjust the performance of the sound-emitting component 10 at low and high frequencies.

[0039] The speaker assembly 10 consists of a sound-amplifying coil 11 and a base 12. The base 12 includes a permanent magnet 121, with one side being the N pole and the other the S pole, and a hole in the center of the permanent magnet 121. A first iron plate 122 and a second iron plate 123 are disposed on the upper and lower surfaces of the permanent magnet 121, respectively. A cylindrical boss 124 is disposed in the center of the second iron plate 123. This cylindrical boss 124 passes through the hole in the center of the permanent magnet 121, and a gap exists between the outer diameter of the cylindrical boss 124 and the hole in the center of the permanent magnet 121, creating a natural magnetic field between the two locations.

[0040] The amplifier coil 11 includes an amplifier disk 111, inside which a diaphragm 112 is disposed. A paper tube 113 is fixedly connected to the center of the diaphragm 112. A copper coil 114 is disposed at the lower end of the paper tube 113, and the copper coil 114 is wound in coils around the outer wall of the paper tube 113. When the copper coil 114 is energized, according to the principle of battery induction, the copper coil 114 generates a magnetic field surrounding the conductor, the strength of which is determined by the magnitude of the current passing through the copper coil 114. The paper tube 113 and the copper coil 114 are inserted into the gap between the outer diameter of the cylindrical boss 124 and the central hole of the permanent magnet 121. When the two magnetic fields come into contact, their respective magnetic fields become entangled, pulling and repelling each other, causing the paper tube 113 to vibrate back and forth, which in turn drives the diaphragm 112 to vibrate up and down. The diaphragm 112 vibrates by pushing air to produce sound, which is amplified by the amplifier disk 111.

[0041] Furthermore, this refers to the phenomenon of energy distribution changes caused by superposition when sound waves emitted by a loudspeaker propagate through space. Its core physical mechanism can be traced back to the principle of sound pressure field superposition described by the wave equation and the Helmholtz equation. In a closed or semi-closed space, when the sound waves emitted by the loudspeaker interact with external noise or reflected waves, the interference effect significantly affects the frequency response characteristics.

[0042] Because low-frequency sound waves (<300Hz) have longer wavelengths, they easily form standing waves with room boundaries, causing abnormal increases or decreases in sound pressure levels at specific frequencies. This can mask the uniformity of bass response from speakers, especially noticeable in small rooms. High-frequency sound waves (>2kHz) have shorter wavelengths and are easily scattered by obstacles or absorbed by sound-absorbing materials, weakening sound detail and positioning accuracy. Furthermore, temporal aliasing can occur between external high-frequency noise and the direct sound from the speakers, reducing the signal-to-noise ratio.

[0043] In this embodiment, refer to Figures 4 to 6 As shown, the sound-absorbing component 20 is installed below the base 12. The sound-absorbing component 20 includes a fixed cavity 21 and a sensing unit 24. The sensing unit 24 increases the sound absorption coefficient at low frequencies and suppresses the sound absorption coefficient at high frequencies. The gap between the fixed cavity 21 and the sensing unit 24 is a filled cavity 21A, which is filled with porous sound-absorbing material. Multiple sound-guiding cavities 22 are provided on the side wall of the fixed cavity 21. A sound-guiding tube 23 is installed above the fixed cavity 21. One end of the sound-guiding tube 23 is connected to the sound-guiding cavity 22, and the other end is connected to the amplifier disk 111. The inner wall of the fixed cavity 21 is also provided with a guide strip 21B, which connects the sound-guiding cavity 22, the sound-guiding tube 23, and the porous sound-absorbing material installed in the filled cavity 21A.

[0044] Preferably, the guide strip 21B can also fix the porous sound-absorbing material in the filling cavity 21A.

[0045] Refer again Figure 2 As shown, the amplifier disk 111 has multiple sound-absorbing cavities 111A arranged circumferentially, and multiple sound-guiding holes 111B are arranged below the sound-absorbing cavities 111A. A sound-guiding tube 23 is installed below the sound-guiding holes 111B. External noise is transmitted to the sound-absorbing assembly 20 through the sound-absorbing cavities 111A and the sound-guiding holes 111B.

[0046] In this embodiment, the induction unit 24 includes a stator disk 241, with multiple iron cores 242 evenly spaced around the inner diameter of the stator disk 241, and induction coils 243 wound around the iron cores 242. A permanent magnet turntable 244 is provided in the middle of the stator disk 241. The rotation of the permanent magnet turntable 244 can cause the induction coils 243 to generate current and generate a magnetic field around itself.

[0047] The stator disk 241 includes a main frame 241A, on which a plurality of accommodating cavities 241B are provided, and a flexible material 241C is provided on the outside of the accommodating cavity 241B. The flexible material 241C is connected to the porous sound-absorbing material installed in the filling cavity 21A.

[0048] The permanent magnet turntable 244 consists of a first permanent magnet disk 244A and a second permanent magnet disk 244B. The teeth of the first permanent magnet disk 244A and the second permanent magnet disk 244B are staggered. A first ball groove 244C is provided in the center of the permanent magnet turntable 244. (Refer to...) Figure 2 and Figure 3 As shown, a second ball groove 115 is provided at the end of the paper tube 113. The second ball groove 115 is disposed through the middle of the permanent magnet turntable 244, and a ball is disposed between the first ball groove 244C and the second ball groove 115. That is, when the paper tube 113 vibrates up and down, it can drive the permanent magnet turntable 244 to rotate through the first ball groove 244C and the second ball groove 115.

[0049] In this embodiment, it is important to clarify that the vertical displacement of the diaphragm 112 differs between low and high frequencies. At low frequencies, a larger displacement is required to move enough air to produce the same sound pressure level as at high frequencies. Therefore, at low frequencies, the displacement amplitude of the diaphragm 112 is larger; at high frequencies, the displacement amplitude of the diaphragm 112 is smaller.

[0050] In other words, at low frequencies, the diaphragm 112 drives the permanent magnet turntable 244 to rotate at a frequency higher than at high frequencies via the paper tube 113, the first ball groove 244C, and the second ball groove 115. The rotation frequency of the permanent magnet turntable 244 affects the rate of change of magnetic flux. According to Faraday's law of electromagnetic induction, at low frequencies, the current generated by the induction coil 243 is greater than at high frequencies.

[0051] Specifically, refer again Figure 5 and Figure 6As shown, the induction coil 243 consists of a first coil 243A and a second coil 243B, which are connected in series. The second coil 243B is located within the accommodating cavity 241B. The accommodating cavity 241B is filled with a magnetorheological fluid not exceeding two-thirds of its own volume. The magnetic particles of the magnetorheological fluid are hydroxyl iron powder with a particle size of 3-5 micrometers and a volume fraction of 30%-50%. The base liquid is silicone oil, water, or ethanol. Without a magnetic field, the magnetic particles are randomly dispersed, and the fluid exhibits a low viscosity similar to a Newtonian fluid, allowing it to flow freely. When a magnetic field is applied, the particles are magnetized and arrange themselves into chain-like or columnar structures along the direction of the magnetic field, causing a sharp increase in fluid viscosity, even exhibiting solid-like properties. After the magnetic field is removed, the chain-like structure disintegrates, the particles redisperse, and the fluid regains its fluidity. This process is reversible and has a rapid response within milliseconds.

[0052] When sound waves propagate, they cause localized shear flow in the magnetorheological fluid. The viscous resistance between molecules converts some of the sound energy into heat energy, thus achieving a sound absorption effect. Therefore, as the viscosity of the magnetorheological fluid increases, the viscous resistance between its molecules also increases, thereby improving its sound absorption performance.

[0053] In this embodiment, refer to Figure 7 As shown, at low frequencies, the current of induction coil 243 increases, the magnetic field strength of induction coil 243 also increases, the viscosity of magnetorheological fluid increases, and the sound absorption coefficient increases; at high frequencies, the current of induction coil 243 decreases, the magnetic field strength of induction coil 243 also decreases, the viscosity of magnetorheological fluid decreases, and the sound absorption coefficient decreases.

[0054] Specifically, according to Ampere's circuital law, the relationship between the magnetic field strength and the current of the induction coil 243 is as follows: the generated magnetic field strength H and the current I satisfy: H = Ni / L, where N represents the number of turns of the coil, L represents the magnetic circuit length, which is related to the geometry of the accommodating cavity 241B, and I represents the coil current. The yield stress of the magnetorheological fluid is also considered. The relationship between the magnetic field strength H and the magnetic field strength H is expressed as: , and All are expressed as material constants.

[0055] Specifically, the viscosity of magnetorheological fluids is related to the shear rate; at a shear rate... Below, the apparent viscosity of the magnetorheological fluid It can be represented as:

[0056]

[0057] in, This indicates the viscosity of the magnetorheological fluid in the absence of a magnetic field. This represents the shear rate caused by acoustic wave vibration.

[0058] Low-frequency sound absorption coefficient With magnetorheological fluid viscosity Related, represented as:

[0059]

[0060] Where f represents the sound wave frequency, c represents the sound speed, and p represents the material density.

[0061] High-frequency sound absorption coefficient This is expressed as: when the magnetic field strength magnetorheological fluid yield stress magnetorheological fluid viscosity ,lead to .

[0062] In this embodiment, by adjusting the current to change the magnetic field strength, the viscosity of the magnetorheological fluid can be precisely controlled, thereby achieving dynamic regulation of the sound absorption performance and accurately matching the sound absorption requirements of the target frequency band. Example 2

[0063] Furthermore, based on the above embodiments, this embodiment also discloses a loudspeaker assembly, which consists of one or more miniature loudspeakers.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A miniature loudspeaker, characterized in that, include: A speaker assembly, comprising a diaphragm and a paper tube, wherein a second ball groove is provided at the end of the paper tube; The sound-absorbing component includes a fixed cavity and a sensing unit, wherein the sensing unit increases the sound absorption coefficient at low frequencies and suppresses the sound absorption coefficient at high frequencies. The space between the fixed cavity and the sensing unit is filled with a porous sound-absorbing material. The sensing unit includes a stator disk, which includes a main frame. The main frame has multiple receiving cavities, and the outer side of each receiving cavity is covered with a flexible material. The stator disk has multiple iron cores evenly spaced along its inner diameter, with induction coils wound around the iron cores. A permanent magnet turntable is located in the center of the stator disk, and a first ball groove is located in the center of the permanent magnet turntable. The second ball groove is disposed through the middle of the permanent magnet turntable and cooperates with the first ball groove. When the paper tube vibrates, the first ball groove and the second ball groove drive the permanent magnet turntable to rotate.

2. The miniature loudspeaker according to claim 1, characterized in that, The induction coil consists of a first coil and a second coil connected in series. The second coil is located inside the accommodating cavity, which is filled with magnetorheological fluid.

3. The miniature loudspeaker according to claim 2, characterized in that, The induction coil generates a greater current at low frequencies than at high frequencies. in, At low frequencies, the current in the induction coil increases, the magnetic field strength of the induction coil increases, the viscosity of the magnetorheological fluid increases, and the sound absorption coefficient increases. At high frequencies, the current in the induction coil decreases, the magnetic field strength of the induction coil decreases, the viscosity of the magnetorheological fluid decreases, and the sound absorption coefficient decreases.

4. The miniature loudspeaker according to claim 1 or 3, characterized in that, The displacement amplitude of the diaphragm at low frequencies is greater than that at high frequencies. Specifically, the rotation frequency of the permanent magnet turntable driven by the paper tube, the first ball groove, and the second ball groove at low frequencies is greater than that at high frequencies.

5. The miniature loudspeaker according to claim 1, characterized in that, The speaker assembly also includes a speaker disk, which has multiple sound-absorbing cavities arranged circumferentially, and multiple sound-guiding holes arranged below the sound-absorbing cavities. A sound-absorbing component is installed below the sound-guiding holes.

6. The miniature loudspeaker according to claim 1, characterized in that, The flexible material is connected to the fixed cavity and the sensing unit by filling with porous sound-absorbing material.

7. The miniature loudspeaker according to claim 1, characterized in that, The permanent magnet turntable consists of a first permanent magnet disk and a second permanent magnet disk, with the teeth of the first permanent magnet disk and the second permanent magnet disk being distributed alternately.

8. The miniature loudspeaker according to claim 1, characterized in that, The speaker assembly consists of a sound-amplifying coil and a base. The base includes a permanent magnet, and a hole is provided in the middle of the permanent magnet. A first iron plate and a second iron plate are provided on the upper and lower surfaces of the permanent magnet. A cylindrical boss is provided in the middle of the second iron plate.

9. The miniature loudspeaker according to claim 8, characterized in that, The amplifier coil includes an amplifier disk, inside which a diaphragm is provided. A paper tube is fixedly connected to the middle of the diaphragm, and a copper coil is provided at the lower end of the paper tube.

10. A loudspeaker assembly, characterized in that, Includes the miniature speaker as described in claim 1.

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