Bone conduction microphones
The present disclosure is of a bone conduction microphone. The bone conduction microphone comprises of a laminated structure and a base structure. The laminated structure is formed by a vibration unit and an acoustic transducer unit. The base structure is configured to load the laminated structure. At least one side of the laminated structure is physically connected to the base structure. The base structure vibrates based on an external vibration signal, the vibration unit deforms 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. A resonant frequency of the bone conduction microphone is within a range of 2.5 kHz-4.5 KHz.
1 . A bone conduction microphone, comprising:
a laminated structure formed by a vibration unit and an acoustic transducer unit; and
a base structure configured to load 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, and the vibration unit deforms 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 resonant frequency of the bone conduction microphone is within a range of 2.5 kHz-4.5 kHz;
the vibration unit includes a suspension membrane structure, the suspension membrane structure is connected to the base structure through a circumferential side of the suspension membrane structure, and the acoustic transducer unit is located on an upper surface or a lower surface of the suspension membrane structure; wherein
the acoustic transducer unit is a ring structure, and a thickness of the suspension membrane structure located in an inner region of the ring structure is greater than a thickness of the suspension membrane structure located in an outer region of the ring structure.
2 . The bone conduction microphone of claim 1 , wherein the resonant frequency of the bone conduction microphone is positively correlated with a stiffness of the vibration unit, or the resonant frequency of the bone conduction microphone is negatively correlated with a mass of the laminated structure.
3 . The bone conduction microphone of claim 1 , wherein the acoustic transducer unit includes a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in sequence from top to bottom.
4 . The bone conduction microphone of claim 3 , wherein the suspension membrane structure includes a plurality of holes, and the plurality of holes are distributed along an inner circumferential direction of the acoustic transducer unit.
5 . The bone conduction microphone of claim 4 , wherein the plurality of holes are circular holes, and radii of the circular holes are within a range of 20 μm-300 μm.
6 . The bone conduction microphone of claim 4 , wherein a shape enclosed by the plurality of holes is consistent with a shape of the acoustic transducer unit.
7 . The bone conduction microphone of claim 4 , wherein the plurality of holes are distributed in a circle along the inner circumferential direction of the acoustic transducer unit, wherein a radius of the circle is within a range of 300 μm-700 μm.
8 . The bone conduction microphone of claim 4 , wherein the acoustic transducer unit at least includes an effective acoustic transducer unit, and a radial distance from an edge of the effective acoustic transducer unit to centers of the plurality of holes is within a range of 50 μm-400 μm.
9 . The bone conduction microphone of claim 8 , wherein an inner diameter of the effective acoustic transducer unit is within a range of 100 μm-700 μm, or an outer diameter of the effective acoustic transducer unit is within a range of 110 μm-710 μm.
10 . The bone conduction microphone of claim 3 , wherein the thickness of the suspension membrane structure the thickness of the suspension membrane structure located in the inner region of the ring structure or the thickness of the suspension membrane structure located in the outer region of the ring structure is within a range of 0.5 μm-10 μm.
11 . The bone conduction microphone of claim 3 , wherein a thickness of the first electrode layer is within a range of 80 nm-250 nm, and a thickness of the second electrode layer is within a range of 80 nm-250 nm.
12 . The bone conduction microphone of claim 3 , wherein a thickness of the piezoelectric layer is within a range of 0.8 μm-5 μm.
13 . The bone conduction microphone of claim 3 , wherein the vibration unit further includes a mass element, wherein the mass element is a cylinder, a radius of a cross-section of the mass element perpendicular to a thickness direction is within a range of 100 μm-700 μm, and a thickness of the mass element is within a range of 20 μm-400 μm.
14 . The bone conduction microphone of claim 3 , wherein a lead structure is arranged on the suspension membrane structure, and the first electrode layer and the second electrode layer are connected to the base structure through the lead structure.
15 . The bone conduction microphone of claim 14 , wherein a width of the lead structure is within a range of 2 μm-100 μm.
16 . The bone conduction microphone of claim 1 , wherein a ratio of an electrical signal intensity to a noise intensity of the bone conduction microphone is 50%-100% of a maximum ratio of the electrical signal intensity to the noise intensity.
17 . 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 through the at least one support arm.
18 . The bone conduction microphone of claim 17 , further comprising a limiting structure located in a hollow position of the base structure, wherein the limiting structure is connected to the base structure, and the limiting structure is located above or below the mass element.
19 . The bone conduction microphone of claim 1 , further comprising at least one damping structure layer, wherein the at least one damping structure layer covers an upper surface, a lower surface, or an inside of the laminated structure.