Bone conduction sound transmission device based on magnetostrictive element

Abstract

The application belongs to the field of sound transmission equipment, and particularly relates to a bone conduction sound transmission equipment based on a magnetostrictive element, which comprises a shell, a containing cavity is arranged on the top of the shell, and an element mounting groove is arranged on the bottom surface of the containing cavity; a magnetostrictive element is arranged in the element mounting groove, the upper end and the lower end of the magnetostrictive element are respectively connected with a first permanent magnet and a second permanent magnet, and a hollow coil is arranged on the outer side of the magnetostrictive element; a sound transmission rod is arranged above the first permanent magnet, and a noise reduction reset assembly for resetting the sound transmission rod is arranged at the opening of the containing cavity. The hollow coil is fixed in a mode that the element mounting groove cooperates with a coil limiting ring, and no additional coil support is needed, so that the overall weight of the equipment is reduced, the high-frequency mechanical vibration requirement of bone conduction can be met, the noise reduction reset assembly is arranged, the vibration noise generated by the magnetostrictive element is effectively blocked, the transmission of the noise in the containing cavity is reduced, and the sound quality effect of sound transmission is ensured.

Description

Technical Field

[0001] This invention belongs to the field of sound transmission devices, and specifically relates to a bone conduction sound transmission device based on a magnetostrictive element. Background Technology

[0002] Magnetostrictive materials are a class of magnetic functional materials that undergo length or volume changes under the influence of an external magnetic field, enabling the conversion between electromagnetic energy and mechanical energy. Among them, supermagnetostrictive materials have a much larger magnetostriction coefficient than traditional magnetostrictive materials, and possess advantages such as high energy conversion efficiency, high energy density, high response speed, high reliability, and simple driving methods. They have been applied in fields such as sonar transducers, micro-displacement actuation, marine exploration, and precision machining.

[0003] However, the actual performance of super magnetostrictive materials when directly applied to sound transmission devices is poor. When using super magnetostrictive rods, permanent magnets need to be installed at both ends, and coils are used to achieve longitudinal expansion and contraction. However, when this structure is used as a mechanical vibration source for bone conduction, it has problems such as insufficient longitudinal expansion rate, poor sound transmission effect, high noise and heavy weight. On the one hand, the magnetic field strength directly affects the expansion and contraction range of the magnetostrictive rod, thus affecting the vibration and sound transmission effect. Since the coil cannot be directly wound around the surface of the magnetostrictive rod, a tubular support is needed to be fitted on the outside of the magnetostrictive rod for support, such as an iron tubular support, i.e., an iron core. Although this can ensure the magnetic field strength, the response speed is slow due to the hysteresis effect, making it difficult to adapt to the high-frequency mechanical vibration requirements of bone conduction. In addition, the weight of the iron core is relatively large, which is difficult to meet the lightweight requirements of some head-mounted sound transmission devices, such as headphones and hearing aids. On the other hand, the permeability of the plastic tubular support is poor, which directly affects the magnetic field strength and reduces the expansion and contraction distance of the magnetostrictive rod, thus affecting the vibration and sound transmission effect. On the other hand, when the magnetostrictive rod is used as a mechanical vibration source for bone conduction, it needs to reciprocate and expand at high frequency, which will generate obvious friction noise. This factor greatly affects the sound transmission quality. In addition, in applications such as headphones and hearing aids, the mechanical vibration source of bone conduction sound transmission devices also needs to meet the requirements of miniaturization. If the assembly shell of the super magnetostrictive rod has problems such as large size or complex assembly, it will be difficult to adapt to the current head-mounted sound transmission devices. Summary of the Invention

[0004] To address the above problems, this invention provides a bone conduction sound transmission device based on a magnetostrictive element.

[0005] A bone conduction sound transmission device based on a magnetostrictive element includes a housing. The top of the housing has a receiving cavity, and the bottom surface of the receiving cavity has an element mounting groove. A cylindrical magnetostrictive element is disposed within the element mounting groove. A first permanent magnet and a second permanent magnet are respectively connected to the upper and lower ends of the magnetostrictive element. A hollow coil is sleeved on the outer side of the magnetostrictive element. A coil limiting ring is provided at the opening of the element mounting groove. The upper and lower ends of the hollow coil abut against the coil limiting ring and the bottom surface of the element mounting groove, respectively, and the inner diameter of the coil limiting ring is larger than the diameter of the first permanent magnet. A sound transmission rod is provided above the first permanent magnet, and the sound transmission rod is connected to a sound transmission plate located outside the housing. A noise reduction and reset assembly for resetting the sound transmission rod is provided at the opening of the receiving cavity.

[0006] Furthermore, a skin-friendly adhesive pad is attached to the upper surface of the sound transmission plate.

[0007] Furthermore, the magnetostrictive element is a magnetostrictive rod made of a super magnetostrictive material.

[0008] Furthermore, the first permanent magnet is provided with a first embedding groove for embedding the upper end of the magnetostrictive element, and the second permanent magnet is provided with a second embedding groove for embedding the lower end of the magnetostrictive element.

[0009] Furthermore, both the receiving cavity and the component mounting slot have circular cross-sections, and the bottom surface of the receiving cavity is provided with a stepped structure near the opening of the component mounting slot. The upper part of the coil limiting ring is provided with a flange that matches the stepped structure.

[0010] Furthermore, the noise reduction and reset assembly includes an elastic cover made of elastic material, the elastic cover having a first through hole in the middle for the sound transmission rod to pass through, the sound transmission rod having a first limiting block at the lower part, the width of the first limiting block being greater than the diameter of the first through hole; a first noise reduction washer and a second noise reduction washer are respectively provided on the upper and lower sides of the first through hole, and both the first noise reduction washer and the second noise reduction washer are sleeved and connected to the outer surface of the sound transmission rod.

[0011] Furthermore, the noise reduction and reset assembly includes a soundproof cover, a spring mounting groove on the bottom center of the soundproof cover, a second through hole for the sound transmission rod to pass through at the top of the spring mounting groove, a second limiting block at the lower part of the sound transmission rod, the width of the second limiting block being greater than the diameter of the second through hole; a third noise reduction washer is provided in the spring mounting groove, a reset spring is provided below the third noise reduction washer, the reset spring is sleeved on the outside of the sound transmission rod, a fourth noise reduction washer is provided between the reset spring and the second limiting block, and the upper and lower ends of the reset spring abut against the third noise reduction washer and the fourth noise reduction washer, respectively.

[0012] Furthermore, a first magnetic material sheet for guiding magnetic field lines is attached to the lower surface of the first permanent magnet, and the diameter of the first magnetic material sheet is larger than the diameter of the first permanent magnet.

[0013] Furthermore, a second magnetic material sheet for guiding magnetic field lines is attached to the upper surface of the second permanent magnet, and the diameter of the second magnetic material sheet is larger than the diameter of the second permanent magnet.

[0014] Furthermore, the bottom of the housing is provided with a fourth embedding groove, the fourth embedding groove is provided with a PCB board, and the top of the fourth embedding groove is provided with a wiring hole for connecting component mounting groove, thereby the PCB board is electrically connected to the hollow coil.

[0015] The beneficial effects of this invention are: (1) The hollow coil is fixed by the combination of the component mounting slot and the coil limiting ring. There is no need to use the bracket sleeved on the outside of the super magnetostrictive rod as a support, thus eliminating the weight of the bracket, ensuring the magnetic field strength, and also adapting to the high frequency mechanical vibration requirements of bone conduction. (2) By setting up a noise reduction and reset component, the friction noise generated by the magnetostrictive element is effectively blocked, which reduces the transmission of noise in the cavity and ensures the sound quality. (3) By guiding the magnetic field lines through the magnetic material sheet, the magnetostrictive element can obtain greater magnetic energy, improve the stretching rate, and ensure the stretching range of the magnetostrictive element; (4) The slotted design of the housing simplifies the installation of magnetostrictive components and PCB boards, avoids complex assembly processes, reduces housing weight, and lowers processing costs.

[0016] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A cross-sectional schematic diagram of the present invention using an elastic cap is shown; Figure 2 A partial cross-sectional schematic diagram of the elastic cap of the present invention is shown; Figure 3 A cross-sectional schematic diagram of the present invention using a soundproof cover is shown; Figure 4 A partial cross-sectional schematic diagram of the soundproof cover of the present invention is shown; Figure 5 A partial structural cross-sectional schematic diagram of the present invention is shown.

[0019] In the diagram: 1. Housing; 2. Coil limiting ring; 3. Receiving cavity; 4. Sound transmission plate; 5. Skin-friendly rubber pad; 6. Sound transmission rod; 7. Elastic cover; 8. First permanent magnet; 9. Magnetostrictive element; 10. Second permanent magnet; 11. PCB board; 12. Hollow coil; 13. First limiting block; 14. First noise reduction washer; 15. Second noise reduction washer; 16. Sound insulation cover; 17. Second limiting block; 18. Third noise reduction washer; 19. Return spring; 20. Fourth noise reduction washer; 21. First magnetic material sheet; 22. Second magnetic material sheet. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 like Figure 1-5 As shown, a bone conduction sound transmission device based on a magnetostrictive element 9 includes a housing 1. The top of the housing 1 has a receiving cavity 3, and the bottom surface of the receiving cavity 3 has an element mounting groove. A cylindrical magnetostrictive element 9 is provided in the element mounting groove. The upper and lower ends of the magnetostrictive element 9 are respectively connected to a first permanent magnet 8 and a second permanent magnet 10. A hollow coil 12 is sleeved on the outside of the magnetostrictive element 9. A coil limiting ring 2 is provided at the opening of the element mounting groove. The upper and lower ends of the hollow coil 12 abut against the coil limiting ring 2 and the bottom surface of the element mounting groove, respectively. The inner diameter of the coil limiting ring 2 is larger than the diameter of the first permanent magnet 8. A sound transmission rod 6 is provided above the first permanent magnet 8. The sound transmission rod 6 is connected to a sound transmission plate 4 located on the outside of the housing 1. A noise reduction and reset assembly for resetting the sound transmission rod 6 is provided at the opening of the receiving cavity 3. This design fixes the hollow coil 12 by cooperating with the component mounting slot and the coil limiting ring 2, eliminating the need for an additional coil support, thereby reducing the overall weight of the device and adapting to the high-frequency mechanical vibration requirements of bone conduction, ensuring sound transmission quality.

[0022] Specifically, the hollow coil 12 is formed by winding enameled copper wire using a mold, placed into the component mounting slot, and fitted onto the outside of the magnetostrictive element 9, with a gap between them. Then, the coil limiting ring 2 is installed to press the hollow coil 12 firmly, thereby fixing the hollow coil 12. The coil limiting ring 2 can be made of plastic, and to ensure stable installation of the coil limiting ring 2, both the receiving cavity 3 and the component mounting slot have circular cross-sections. The bottom surface of the receiving cavity 3 has a stepped structure near the opening of the component mounting slot, and the upper part of the coil limiting ring 2 has a flange adapted to the stepped structure.

[0023] To improve the comfort of bone conduction sound transmission, a skin-friendly adhesive pad 5 is attached to the upper surface of the sound transmission plate 4. The skin-friendly adhesive pad 5 can be made of silicone.

[0024] The magnetostrictive element 9 is a super magnetostrictive rod made of a super magnetostrictive material. The first permanent magnet 8 has a first embedding groove for embedding into the upper end of the magnetostrictive element 9, and the second permanent magnet 10 has a second embedding groove for embedding into the lower end of the magnetostrictive element 9, thus facilitating the installation of the super magnetostrictive rod. The magnetic directions of the first permanent magnet 8 and the second permanent magnet 10 are aligned, and both have circular cross-sections. Specifically, both the first permanent magnet 8 and the second permanent magnet 10 can be high-performance neodymium iron boron magnets. Furthermore, a third embedding groove is provided at the bottom of the element mounting groove to facilitate the embedding and fixation of the second permanent magnet 10 within the third embedding groove.

[0025] A first magnetic material sheet 21 for guiding magnetic field lines is attached to the lower surface of the first permanent magnet 8. The diameter of the first magnetic material sheet 21 is larger than the diameter of the first permanent magnet 8. A second magnetic material sheet 22 for guiding magnetic field lines is attached to the upper surface of the second permanent magnet 10. The diameter of the second magnetic material sheet 22 is larger than the diameter of the second permanent magnet 10. By using the first magnetic material sheet 21 and the second magnetic material sheet 22 to organize the magnetic field lines, the magnetic field lines are made more concentrated, ensuring the longitudinal expansion and contraction effect of the magnetostrictive element 9. Preferably, both the first magnetic material sheet 21 and the second magnetic material sheet 22 can be made of iron sheets with high magnetic permeability. It should be noted that in the actual processing of magnets, their edges often have burrs or certain obtuse angles, which affect the dissipation of the magnetic field, resulting in relatively loose magnetic field lines. By using a thin iron sheet in conjunction with the magnet to organize the magnetic field lines, the magnetic field lines can be concentrated, the magnetic field can be strengthened, and thus the longitudinal expansion and contraction effect of the magnetostrictive element 9 can be improved. Specifically, when the housing 1 is a non-metallic shell, a first magnetic material sheet 21 and a second magnetic material sheet 22 need to be respectively installed below the first permanent magnet 8 and above the second permanent magnet 10; when the housing 1 is a metallic shell, only the first magnetic material sheet 21 needs to be installed below the first permanent magnet 8. To facilitate the installation of the magnetostrictive element 9, the first magnetic material sheet 21 has a first opening in the middle that matches the first embedding groove; the second magnetic material sheet 22 has a second opening in the middle that matches the second embedding groove.

[0026] The bottom of the housing 1 is provided with a fourth embedding groove, and a PCB board 11 is provided in the fourth embedding groove. The top of the fourth embedding groove is provided with a wiring hole for connecting component mounting groove, so that the PCB board 11 is electrically connected to the hollow coil 12, thereby facilitating wiring. In addition, the housing 1 is an integrated design with better structural strength and simple assembly process.

[0027] Example 2 like Figure 1-2As shown, a bone conduction sound transmission device based on a magnetostrictive element 9 includes a housing 1. The top of the housing 1 has a receiving cavity 3, and the bottom surface of the receiving cavity 3 has an element mounting groove. A cylindrical magnetostrictive element 9 is placed inside the element mounting groove. The upper and lower ends of the magnetostrictive element 9 are respectively connected to a first permanent magnet 8 and a second permanent magnet 10. A hollow coil 12 is sleeved on the outside of the magnetostrictive element 9. A coil limiting ring 2 is provided at the opening of the element mounting groove. The upper and lower ends of the hollow coil 12 abut against the coil limiting ring 2 and the bottom surface of the element mounting groove, respectively. The inner diameter of the coil limiting ring 2 is larger than the diameter of the first permanent magnet 8. A sound transmission rod 6 is positioned above the magnet 8, and the sound transmission rod 6 is connected to a sound transmission plate 4 located on the outside of the housing 1. A noise reduction and reset assembly for resetting the sound transmission rod 6 is provided at the opening of the receiving cavity 3. The noise reduction and reset assembly includes an elastic cover 7 made of elastic material. The center of the elastic cover 7 has a first through hole for the sound transmission rod 6 to pass through. The lower part of the sound transmission rod 6 has a first limiting block 13, the width of which is greater than the diameter of the first through hole. A first noise reduction washer 14 and a second noise reduction washer 15 are respectively provided on the upper and lower sides of the first through hole, and both the first noise reduction washer 14 and the second noise reduction washer 15 are fitted and connected to the outer surface of the sound transmission rod 6. This design utilizes the elasticity of the elastic cover 7 to achieve the reset process of the sound transmission rod 6, and reduces the transmission of friction noise through the first noise reduction washer 14 and the second noise reduction washer 15.

[0028] Specifically, the lower middle part of the sound transmission plate 4 is provided with a first block-shaped protrusion, the bottom of the first block-shaped protrusion is provided with a first bolt hole, the inner wall of the first bolt hole is provided with a first internal thread, and the outer surface of the upper part of the sound transmission rod 6 is provided with a first external thread that matches the first internal thread. Then, the upper part of the sound transmission rod 6 is screwed into the first bolt hole and connected to the first block-shaped protrusion by the thread, thereby facilitating the installation between the sound transmission plate 4 and the sound transmission rod 6.

[0029] The elastic cover 7 can be made of spring steel sheet, and the outer side of the elastic cover 7 is fixed to the housing 1 by the first bolt and covers the upper opening of the receiving cavity 3. In order to further improve the repositioning effect of the elastic cover 7 on the sound transmission rod 6, the elastic cover 7 is provided with a recess, and the first through hole is located at the center of the recess. In addition, the cross-section of the recess is an inverted isosceles trapezoidal structure.

[0030] Both the first noise-reducing washer 14 and the second noise-reducing washer 15 can be made of rubber, giving them good wear resistance. Specifically, the first noise-reducing washer 14 is disposed between the block-shaped protrusion and the elastic cover 7, and the second noise-reducing washer 15 is disposed between the elastic cover 7 and the first limiting block 13.

[0031] Example 3 like Figure 3-4As shown, a bone conduction sound transmission device based on a magnetostrictive element 9 includes a housing 1. A receiving cavity 3 is provided at the top of the housing 1, and an element mounting groove is formed on the bottom surface of the receiving cavity 3. A cylindrical magnetostrictive element 9 is placed inside the element mounting groove. A first permanent magnet 8 and a second permanent magnet 10 are respectively connected to the upper and lower ends of the magnetostrictive element 9. A hollow coil 12 is sleeved on the outside of the magnetostrictive element 9. A coil limiting ring 2 is provided at the opening of the element mounting groove. The upper and lower ends of the hollow coil 12 abut against the coil limiting ring 2 and the bottom surface of the element mounting groove, respectively, and the inner diameter of the coil limiting ring 2 is larger than the diameter of the first permanent magnet 8. A sound transmission rod 6 is provided above the first permanent magnet 8, and the sound transmission rod 6 is connected to a sound transmission plate located outside the housing 1. 4. A noise reduction and reset assembly for resetting the sound transmission rod 6 is provided at the opening of the receiving cavity 3. The noise reduction and reset assembly includes a soundproof cover 16, a spring mounting groove on the bottom center of the soundproof cover 16, a second through hole for the sound transmission rod 6 to pass through at the top of the spring mounting groove, a second limiting block 17 at the lower part of the sound transmission rod 6, the width of the second limiting block 17 being larger than the diameter of the second through hole; a third noise reduction washer 18 is provided in the spring mounting groove, a reset spring 19 is provided below the third noise reduction washer 18, the reset spring 19 is sleeved on the outside of the sound transmission rod 6, a fourth noise reduction washer 20 is provided between the reset spring 19 and the second limiting block 17, and the upper and lower ends of the reset spring 19 abut against the third noise reduction washer 18 and the fourth noise reduction washer 20 respectively. This design uses the elasticity of the reset spring 19 to achieve the reset process of the sound transmission rod 6, and the soundproof cover 16, the third noise reduction washer 18 and the fourth noise reduction washer 20 work together to reduce the transmission of friction noise.

[0032] Specifically, the lower middle part of the sound transmission plate 4 has a second block-shaped protrusion, the bottom of which has a second bolt hole. The inner wall of the second bolt hole has a second internal thread, and the outer surface of the upper part of the sound transmission rod 6 has a second external thread that matches the second internal thread. The upper part of the sound transmission rod 6 is screwed into the second bolt hole and connected to the second block-shaped protrusion by the thread, thus facilitating the installation between the sound transmission plate 4 and the sound transmission rod 6. The third noise reduction washer 18 and the fourth noise reduction washer 20 are both fitted onto the outer surface of the sound transmission rod 6. The lower part of the third noise reduction washer 18 has an annular protrusion that matches the inner contour of the spring mounting groove to reduce the transmission of frictional noise. To further improve the noise reduction effect, the annular protrusion located at the lower part of the third noise reduction washer 18 extends downward and abuts against the upper surface of the fourth noise reduction washer 20, so that the return spring 19 can be set in the space enclosed by the third noise reduction washer 18, the annular protrusion, and the fourth noise reduction washer 20.

[0033] The soundproof cover 16 can be made of engineering plastic, and the outer side of the soundproof cover 16 is fixed to the housing 1 by the second bolt and covers the upper opening of the receiving cavity 3. Using engineering plastic material can reduce the increase in the overall weight of the equipment and ensure the structural strength of the soundproof cover 16. The third noise reduction washer 18 and the fourth noise reduction washer 20 can both be made of rubber, giving them better wear resistance.

[0034] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bone conduction sound transmission device based on a magnetostrictive element, characterized in that, Includes a housing, the top of which has a receiving cavity, and the bottom surface of which has a component mounting groove; The component mounting slot is provided with a cylindrical magnetostrictive element. The upper and lower ends of the magnetostrictive element are respectively connected to a first permanent magnet and a second permanent magnet. A hollow coil is sleeved on the outside of the magnetostrictive element. The opening of the component mounting slot is provided with a coil limiting ring. The upper and lower ends of the hollow coil abut against the coil limiting ring and the bottom surface of the component mounting slot, respectively. The inner diameter of the coil limiting ring is larger than the diameter of the first permanent magnet. A sound transmission rod is provided above the first permanent magnet, and the sound transmission rod is connected to a sound transmission plate located on the outside of the housing; The opening of the receiving cavity is provided with a noise reduction and reset assembly for resetting the sound transmission rod. The noise reduction and reset assembly includes an elastic cover made of elastic material, the elastic cover having a first through hole in the middle for the sound transmission rod to pass through, and the sound transmission rod having a first limiting block at the lower part, the width of the first limiting block being greater than the diameter of the first through hole; A first noise-reducing washer and a second noise-reducing washer are respectively provided on the upper and lower sides of the first through hole, and both the first noise-reducing washer and the second noise-reducing washer are sleeved and connected to the outer surface of the sound transmission rod.

2. The bone conduction sound transmission device based on a magnetostrictive element as described in claim 1, characterized in that, The outer side of the elastic cover is fixed to the housing by the first bolt and covers the upper opening of the receiving cavity.

3. The bone conduction sound transmission device based on a magnetostrictive element as described in claim 1, characterized in that, The elastic cap has a recessed portion, and the first through hole is located at the center of the recessed portion.

4. The bone conduction sound transmission device based on a magnetostrictive element as described in claim 1, characterized in that, The lower middle part of the sound transmission plate is provided with a first block-shaped protrusion, the first noise reduction washer is disposed between the first block-shaped protrusion and the elastic cover, and the second noise reduction washer is disposed between the elastic cover and the first limiting block.

5. A bone conduction sound transmission device based on a magnetostrictive element, characterized in that, Includes a housing, the top of which has a receiving cavity, and the bottom surface of which has a component mounting groove; The component mounting slot is provided with a cylindrical magnetostrictive element. The upper and lower ends of the magnetostrictive element are respectively connected to a first permanent magnet and a second permanent magnet. A hollow coil is sleeved on the outside of the magnetostrictive element. The opening of the component mounting slot is provided with a coil limiting ring. The upper and lower ends of the hollow coil abut against the coil limiting ring and the bottom surface of the component mounting slot, respectively. The inner diameter of the coil limiting ring is larger than the diameter of the first permanent magnet. A sound transmission rod is provided above the first permanent magnet, and the sound transmission rod is connected to a sound transmission plate located on the outside of the housing; The opening of the receiving cavity is provided with a noise reduction and reset assembly for resetting the sound transmission rod. The noise reduction and reset assembly includes a soundproof cover, a spring mounting groove is provided on the bottom center side of the soundproof cover, a second through hole for the sound transmission rod to pass through is provided on the top of the spring mounting groove, and a second limiting block is provided on the lower part of the sound transmission rod, the width of the second limiting block being greater than the diameter of the second through hole; A third noise-reducing washer is provided in the spring mounting groove, and a reset spring is provided below the third noise-reducing washer. The reset spring is sleeved on the outside of the sound transmission rod. A fourth noise-reducing washer is provided between the reset spring and the second limiting block, and the upper and lower ends of the reset spring abut against the third noise-reducing washer and the fourth noise-reducing washer, respectively.

6. A bone conduction sound transmission device based on a magnetostrictive element as described in claim 5, characterized in that, The third and fourth noise-reducing washers are both sleeved and connected to the outer surface of the sound transmission rod. The lower part of the third noise-reducing washer has an annular protrusion that matches the inner contour of the spring mounting groove. The annular protrusion extends downward and abuts against the upper surface of the fourth noise-reducing washer, so that the reset spring is located in the space enclosed by the third noise-reducing washer, the annular protrusion and the fourth noise-reducing washer.

Images