Bone conduction microphone
A bone conduction microphone is provided. The bone conduction microphone may include a laminated structure formed by a vibration unit and an acoustic transducer unit. The bone conduction microphone may include a base structure configured to carry the laminated structure. At least one side of the laminated structure may be physically connected to the base structure. The base structure may vibrate based on an external vibration signal. The vibration unit may be deformed in response to the vibration of the base structure. The acoustic transducer unit may generate an electrical signal based on the deformation of the vibration unit. The bone conduction microphone may include at least one damping structural layer. The at least one damping structural layer may be arranged on an upper surface, a lower surface, and/or an interior of the laminated structure, and the at least one damping layer may be connected to the base structure.
1. A bone conduction microphone, comprising:
a laminated structure formed by a vibration unit and an acoustic transducer unit;
a base structure configured to carry the laminated structure, at least one side of the laminated structure being physically connected to the base structure, wherein
the base structure vibrates based on an external vibration signal,
the vibration unit is deformed in response to the vibration of the base structure, and
the acoustic transducer unit generates an electrical signal based on the deformation of the vibration unit, wherein a distance from the acoustic transducer unit to a connection between the laminated structure and the base structure is smaller than a distance from the acoustic transducer unit to a free end of the laminated structure, and an area covered by the acoustic transducer unit on the vibration unit is not greater than ½ of an area of the vibration unit.
2. The bone conduction microphone of claim 1 , wherein the area covered by the acoustic transducer unit on the vibration unit is not greater than ¼ of the area of the vibration unit.
3. The bone conduction microphone of claim 1 , wherein the bone conduction microphone further includes at least one damping structural layer which is arranged on an upper surface, a lower surface, or an interior of the laminated structure, and the at least one damping structural layer is connected to the base structure.
4. The bone conduction microphone of claim 3 , wherein a natural frequency of the laminated structure is located in a voice frequency range, a loss factor of the at least one damping structural layer is in a range of 0.4-100.
5. The bone conduction microphone of claim 4 , wherein a Young's modulus of the material of the at least one damping structural layer is in a range of 10 9 Pa˜10 10 Pa, a density of the material of the at least one damping structural layer is in a range of 1.1×10 3 kg/m 3 ˜2×10 3 kg/m 3 , a thickness of the at least one damping structural layer is in a range of 0.1 um˜5 um, and the loss factor of the at least one damping structural layer is in a range of 4-20.
6. The bone conduction microphone of claim 4 , wherein a Young's modulus of the material of the at least one damping structural layer is in a range of 10 6 Pa˜10 7 Pa, a density of the material of the at least one damping structural layer is in a range of 0.7×10 3 kg/m 3 ˜1.2×10 3 kg/m 3 , a thickness of the at least one damping structural layer is in a range of 5 um˜80 um, and the loss factor of the at least one damping structural layer is in a range of 30-100.
7. The bone conduction microphone of claim 4 , wherein a Young's modulus of the material of the at least one damping structural layer is in a range of 10 6 Pa˜10 7 Pa, a density of the material of the at least one damping structural layer is in a range of 0.7×10 3 kg/m 3 ˜1.2×10 3 kg/m 3 , a thickness of the at least one damping structural layer is in a range of 0.1 um˜10 um, and the loss factor of the at least one damping structural layer is set to be in a range of 0.4-1.5.
8. The bone conduction microphone of claim 3 , wherein a Poisson's ratio of the material of the at least one damping structural layer is in a range of 0.4˜0.5.
9. The bone conduction microphone of claim 3 , wherein the base structure includes an inner-hollow frame structure, one end of the laminated structure is connected to the base structure or the at least one damping structural layer, and the other end of the laminated structure is suspended in a hollow position of the base structure.
10. The bone conduction microphone of claim 1 , wherein
the vibration unit includes a suspended film structure, and
the acoustic transducer unit includes a first electrode layer, a piezoelectric layer, and a second electrode layer that are arranged in sequence from top to bottom, wherein
the suspended film structure is connected with the base structure through a peripheral side of the suspended film structure, and
the acoustic transducer unit is arranged on an upper surface or a lower surface of the suspended film structure.
11. The bone conduction microphone of claim 10 , wherein the suspended film structure includes a plurality of holes, and the plurality of holes are arranged along a circumference of the acoustic transducer unit.
12. The bone conduction microphone of claim 10 , wherein the vibration unit further includes a mass element, and the mass element is arranged on the upper surface or the lower surface of the suspended film structure.
13. The bone conduction microphone of claim 12 , wherein
the acoustic transducer unit and the mass element are arranged on different sides of the suspended film structure, respectively; or
the acoustic transducer unit and the mass element are arranged on the same side of the suspended film structure, wherein the acoustic transducer unit is a ring-shaped structure, the ring-shaped structure is arranged along a circumference of the mass element.
14. The bone conduction microphone of claim 1 , wherein the vibration unit includes at least one support arm and a mass element, and the mass element is connected to the base structure via the at least one support arm.
15. The bone conduction microphone of claim 14 , wherein the acoustic transducer unit is arranged on an upper surface, a lower surface, or an interior of the at least one support arm.
16. The bone conduction microphone of claim 15 , wherein the acoustic transducer unit includes a first electrode layer, a piezoelectric layer, and a second electrode layer that are arranged in sequence from top to bottom, and the first electrode layer or the second electrode layer is connected to the upper surface or the lower surface of the at least one support arm.
17. The bone conduction microphone of claim 16 , wherein the mass element is arranged on an upper surface or a lower surface of the first electrode layer or the second electrode layer.
18. The bone conduction microphone of claim 17 , wherein an area of the first electrode layer, the piezoelectric layer, and/or the second electrode layer is not greater than an area of the support arm, and part or all of the first electrode layer, the piezoelectric layer, and/or the second electrode layer cover the upper surface or the lower surface of the at least one support arm.
19. The bone conduction microphone of claim 18 , wherein the first electrode layer, the piezoelectric layer, and the second electrode layer of the acoustic transducer unit are close to a connection between the mass element or/and the support arm and the base structure.
20. The bone conduction microphone of claim 16 , wherein the at least one support arm includes at least one elastic layer, and the at least one elastic layer is arranged on an upper surface or a lower surface of a first electrode layer or a second electrode layer.