Double-magnetic moving coil loudspeaker based on Helmholtz resonant cavity

Abstract

The utility model discloses a double-magnetic moving coil loudspeaker based on a Helmholtz resonant cavity, which comprises a loudspeaker frame, a voice coil diaphragm assembly arranged on the loudspeaker frame, and a magnetic circuit system arranged in the loudspeaker frame, a labyrinth cavity is further arranged in the loudspeaker frame, the lower portion of the labyrinth cavity is communicated with the lower groove, the upper portion of the labyrinth cavity is communicated with the upper groove through a through hole, and the upper groove, the through hole, the labyrinth cavity and the lower groove jointly form a Helmholtz resonant cavity. The magnetic circuit structure of the double magnets, the acoustic labyrinth cavity and the natural felt sound absorption layer is adopted, the magnetic field utilization rate can be effectively improved, the high-frequency response can be improved, and distortion can be reduced.

Description

Technical Field

[0001] This utility model belongs to the field of loudspeaker technology, specifically relating to a dual-magnetic moving coil loudspeaker based on a Helmholtz resonant cavity. Background Technology

[0002] Existing conventional moving-coil loudspeakers employ a single magnetic circuit structure, resulting in an uneven magnetic field distribution within the magnetic gap. This causes significant changes in magnetic flux density as the voice coil moves up and down within the magnetic gap, leading to a driving force loss of over 15%. Consequently, the low driving force reduces the loudspeaker's sensitivity. Furthermore, miniaturized designs limit the total voice coil travel. To improve sound sensitivity, a larger voice coil travel is required. However, due to the uneven magnetic field distribution, this travel exceeds the nonlinear region of the magnetic circuit, inevitably resulting in a total harmonic distortion (THD) greater than 1%.

[0003] Currently, the main approaches are using two magnets of the same size and two magnets of different sizes. In the same-size magnet approach, one magnet is placed below the other, and the two magnets have opposite magnetic properties. The two-magnet approach, as disclosed in patent CN208691554U, is a dual-magnetic-circuit speaker where the two magnets are coaxially distributed with opposite polarities to address issues such as low magnetic energy utilization. However, it still has the following drawbacks:

[0004] The standing waves and reflections in the cavity of a moving loudspeaker cause fluctuations in the very high frequency range of the frequency response exceeding ±3dB. Existing solutions include attaching sound-absorbing materials (such as foam) to the back of the frame, but such materials only work on a single frequency band and cannot ensure the smoothness of the overall frequency bandwidth.

[0005] The information disclosed in the above background section is only intended to enhance the understanding of the overall background of this utility model, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a dual-magnetic moving coil loudspeaker based on a Helmholtz resonant cavity, which adopts a practical dual-magnetic and acoustic labyrinth cavity loudspeaker structure, effectively improving magnetic field utilization, enhancing high-frequency response, and reducing distortion.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A dual-magnetic moving coil loudspeaker based on a Helmholtz resonant cavity includes a loudspeaker frame, a voice coil diaphragm assembly mounted on the loudspeaker frame, and a magnetic circuit system mounted inside the loudspeaker frame. The loudspeaker frame has an upper groove and a lower groove respectively. A labyrinth cavity is also provided inside the loudspeaker frame. The lower part of the labyrinth cavity communicates with the lower groove, and the upper part of the labyrinth cavity communicates with the upper groove through a through-hole. The upper groove, the through-hole, the labyrinth cavity, and the lower groove together form a Helmholtz resonant cavity.

[0009] Specifically, the magnetic circuit system includes an inner annular magnet and an outer annular magnet coaxially arranged in the upper groove, and an inner annular magnetic guide plate and an outer annular magnetic guide plate are respectively arranged on the upper surface of the inner annular magnet and the outer annular magnet.

[0010] Specifically, the voice coil diaphragm assembly includes a diaphragm and a voice coil. The diaphragm is fitted with the raised edge of the upper groove, and the voice coil is disposed below the diaphragm. The lower part of the voice coil is disposed between the inner annular magnet and the outer annular magnet.

[0011] By using a dual coaxial magnetic circuit, the lower part of the voice coil is positioned between the inner and outer ring magnets, placing the voice coil in a symmetrical and high-density magnetic field region. This helps to linearize the driving force, significantly improves the magnetic flux density in the voice coil's moving region, enhances magnetic energy utilization, and thus improves the speaker's driving efficiency.

[0012] Specifically, the through hole connects to the gap between the inner annular magnet and the outer annular magnet, as well as the inner hole of the inner annular magnet.

[0013] By setting through holes to connect the gap between the inner and outer annular magnets, as well as the inner hole of the inner annular magnet, the back pressure airflow formed inside the upper groove cavity during voice coil vibration can be effectively guided and released, avoiding local accumulation of airflow between magnets and inside the inner hole, thereby reducing air damping and compression effects and reducing the resistance of voice coil movement.

[0014] Specifically, the labyrinth cavity is a circular cavity, and the width of the circular cavity is greater than the width of the lower groove.

[0015] The enlarged circular cavity structure design avoids sharp-angle reflections and energy concentration during sound wave propagation, allowing sound waves to be reflected and dissipated evenly multiple times within the cavity, further reducing the probability of standing wave formation. The narrowed lower groove structure at the outlet increases the airflow speed through this area, thereby improving the efficiency of the Helmholtz resonator and enhancing its resonance absorption effect at specific frequencies.

[0016] Specifically, a natural felt sound-absorbing layer is also provided at the bottom of the lower groove, and the natural felt sound-absorbing layer has a mesh structure.

[0017] Specifically, the inner and outer annular magnets are magnetized along the vibration direction of the voice coil diaphragm assembly, and their magnetic directions are opposite.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This design utilizes coaxially arranged inner and outer ring magnets with opposite magnetic directions to create a uniform and efficient magnetic field distribution. This minimizes driving force fluctuations during the voice coil's vertical vibration and significantly reduces total harmonic distortion (THD). Simultaneously, a labyrinthine cavity within the frame, combined with upper and lower grooves and through-holes, constructs a Helmholtz resonant cavity with specific acoustic characteristics. This effectively absorbs and attenuates cavity standing waves, significantly improving high-frequency response fluctuations and resulting in a smoother overall frequency response curve. Furthermore, a natural felt sound-absorbing layer at the bottom of the lower groove further enhances the absorption of mid-to-high frequency noise, achieving a wider and more refined sound performance. Through these designs, this invention significantly improves magnetic energy utilization, acoustic quality, and system stability, making it particularly suitable for high-fidelity loudspeaker applications. Attached Figure Description

[0020] Figure 1 This is an exploded schematic diagram of a dual-magnetic-coil loudspeaker based on a Helmholtz resonant cavity according to this utility model.

[0021] Figure 2 This is a cross-sectional view of a dual-magnetic-coil loudspeaker based on a Helmholtz resonant cavity according to this utility model.

[0022] In the diagram, 1-voice coil diaphragm assembly; 2-inner annular magnetic guide plate; 3-outer annular magnetic guide plate; 4-inner annular magnet; 5-outer annular magnet; 6-speaker basket; 7-natural felt sound-absorbing layer; 8-upper groove; 9-lower groove; 10-labyrinth cavity; 11-through hole; 12-diaphragm; 13-voice coil. Detailed Implementation

[0023] To explain the technical content, objectives, and effects of this utility model in detail, the following description is provided in conjunction with embodiments and accompanying drawings. In the description of these embodiments, it should be understood that terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings and are used only for the convenience of describing this embodiment and simplifying the description. They do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0024] The technical solution adopted in this embodiment is a dual-magnetic moving-coil loudspeaker based on a Helmholtz resonant cavity, such as... Figure 1 The exploded view shows that it mainly includes a coil diaphragm assembly 1, an inner annular magnetic guide plate 2, an outer annular magnetic guide plate 3, an inner annular magnet 4, an outer annular magnet 5, a speaker frame 6, and a natural felt sound-absorbing layer 7.

[0025] As a preferred technical solution in this embodiment, refer to Figure 1 , 2 The speaker frame 6 shown has an upper groove 8 and a lower groove 9 respectively. The speaker frame 6 also has a labyrinth cavity 10 with a circular cavity structure. The lower part of the labyrinth cavity 10 is connected to the lower groove 9, and the width of the labyrinth cavity 10 is greater than the width of the lower groove 9. The upper part of the labyrinth cavity 10 is connected to the upper groove 8 through a through hole 11. The upper groove 8, the through hole 11, the labyrinth cavity 10 and the lower groove 9 together form a Helmholtz resonant cavity.

[0026] As a preferred technical solution in this embodiment, the magnetic circuit system installation reference is... Figure 2 As shown, an inner annular magnet 4 and an outer annular magnet 5 are coaxially arranged within the upper groove 8. Specifically, after being magnetized, the inner and outer magnets are fixed to the upper groove 8 with glue. The inner annular magnetic guide plate 2 and the outer annular magnetic guide plate 3 are glued above the inner and outer magnets. The voice coil diaphragm assembly 1 includes a diaphragm 12 and a voice coil 13. The diaphragm 12 is attached to the convex edge of the upper groove 8, and the voice coil 13 is located below the diaphragm 12. The lower part of the voice coil 13 is located between the inner annular magnet 4 and the outer annular magnet 5. The direction of the magnetic poles can be either the inner magnetic N pole pointing upwards and the outer magnetic N pole pointing downwards, or the inner magnetic N pole pointing downwards and the outer magnetic N pole pointing upwards. The magnetization is mainly along the vibration direction of the voice coil diaphragm assembly, and the magnetic directions are opposite. The inner annular magnetic guide plate 2 and the outer annular magnetic guide plate 3 act as a washer, that is, they conduct magnetism and are not magnetic themselves.

[0027] The through hole 11 is configured to at least partially or completely connect to the gap between the inner annular magnet 4 and the outer annular magnet 5, and is configured to connect to the inner hole of the inner annular magnet 4.

[0028] As a preferred technical solution in this embodiment, a natural felt sound-absorbing layer 7 is also provided at the bottom of the lower groove 9, and the natural felt sound-absorbing layer 7 has a mesh structure.

[0029] This embodiment employs a dual-magnetic scheme with both internal and external magnets, and adds an acoustic labyrinth channel. The dual magnets significantly increase the magnetic field density distribution, effectively improving magnetic field utilization and thus enhancing speaker sensitivity. When the speaker diaphragm reciprocates, sound waves are also generated below the diaphragm, in the magnetic circuit gap. Due to the reflection of these sound waves within the cavity, standing waves are easily created, leading to an unsmooth frequency response and increased high-frequency fluctuations. This embodiment adds an acoustic labyrinth cavity within the frame behind the magnet. When sound waves are generated behind the diaphragm, they can enter the labyrinth cavity from the labyrinth opening, effectively improving standing waves and high-frequency fluctuations. The labyrinth space behind the magnet is the Helmholtz resonant cavity. (The formula is used to...) S represents the cross-sectional area of ​​the channel, L represents the channel length, and V represents the volume of the Helmholtz resonant cavity. The resonant frequency can be effectively adjusted by modifying these parameters, and phase interference suppresses the resonance peak in the 5kHz-12kHz frequency band. A natural felt sound-absorbing layer covers the labyrinth's exit, absorbing residual high-frequency noise with an attenuation rate ≥20dB above 12kHz. The labyrinth and felt work together to achieve multi-band damping adjustment: a damping coefficient ≥0.8 for low frequencies (0.5-2kHz), ≤0.3 for high frequencies (5-20kHz), and a frequency response curve fluctuation ≤±1.5dB.

[0030] Although the present invention has been described in detail above with specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A Helmholtz resonant cavity dual-magnetic moving coil loudspeaker, comprising a loudspeaker frame (6), a voice coil diaphragm assembly (1) mounted on the loudspeaker frame (6), and a magnetic circuit system mounted within the loudspeaker frame (6), characterized in that: The speaker frame (6) is provided with an upper groove (8) and a lower groove (9) on the top and bottom respectively. A labyrinth cavity (10) is also provided inside the speaker frame (6). The lower part of the labyrinth cavity (10) is connected to the lower groove (9), and the upper part of the labyrinth cavity (10) is connected to the upper groove (8) through a through hole (11). The upper groove (8), the through hole (11), the labyrinth cavity (10), and the lower groove (9) together form a Helmholtz resonant cavity.

2. The dual-magnetic-coil loudspeaker based on a Helmholtz resonant cavity according to claim 1, characterized in that: The magnetic circuit system includes an inner annular magnet (4) and an outer annular magnet (5) coaxially arranged in the upper groove (8). The upper surfaces of the inner annular magnet (4) and the outer annular magnet (5) are respectively provided with an inner annular magnetic guide plate (2) and an outer annular magnetic guide plate (3).

3. The dual-magnetic-coil loudspeaker based on a Helmholtz resonant cavity according to claim 2, characterized in that: The voice coil diaphragm assembly (1) includes a diaphragm (12) and a voice coil (13). The diaphragm (12) is attached to the convex edge of the upper groove (8). The voice coil (13) is disposed below the diaphragm (12). The lower part of the voice coil (13) is disposed between the inner annular magnet (4) and the outer annular magnet (5).

4. The dual-magnetic-coil loudspeaker based on a Helmholtz resonant cavity according to claim 2, characterized in that: The through hole (11) connects the gap between the inner annular magnet (4) and the outer annular magnet (5), as well as the inner hole of the inner annular magnet (4).

5. The dual-magnetic-coil loudspeaker based on a Helmholtz resonant cavity according to claim 1, characterized in that: The labyrinth cavity (10) is a circular cavity, and the width of the circular cavity is greater than the width of the lower groove (9).

6. The dual-magnetic-coil loudspeaker based on a Helmholtz resonant cavity according to claim 1, characterized in that: The bottom of the lower groove (9) is also provided with a natural felt sound-absorbing layer (7), which is a mesh structure.

7. The dual-magnetic-coil loudspeaker based on a Helmholtz resonant cavity according to claim 2, characterized in that: The inner annular magnet (4) and the outer annular magnet (5) are magnetized along the vibration direction of the voice coil diaphragm assembly (1), and the magnetic directions are opposite.

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