MEMS speaker

Abstract

Provided is a MEMS speaker, comprising: a supporting structure, the supporting structure comprising a supporting body and a sound hole extending from one end of the supporting body through to the other end; a diaphragm, the diaphragm being fixed to an inner peripheral side of the supporting body and located within the sound hole, and the diaphragm being used for emitting amplitude-modulated ultrasonic waves; and an acoustic valve, the acoustic valve comprising a valve body which has a peripheral edge fixed to the supporting body and is located within the sound hole, and a variable cross-section valve hole extending from one end of the valve body through to the other end, wherein the variable cross-section valve hole enables the amplitude-modulated ultrasonic waves passing therethrough to be demodulated into modulated sound waves. The sound wave demodulation efficiency and amplitude of the MEMS speaker of the present invention can be improved, thereby improving the acoustic performance of the MEMS speaker.

Description

MEMS speakers Technical Field

[0001] The present invention relates to the technical field of electroacoustic conversion, and in particular to a MEMS loudspeaker. Background Art

[0002] A speaker is a transducer device that converts electrical signals into acoustic signals. Speakers are widely used in portable electronic products, such as mobile phones and tablets, to convert audio signals into sound for playback. The increasing miniaturization of portable electronic products has driven the increasing miniaturization of speakers. A speaker's sound pressure level (SPL) and harmonic distortion (THD) are important indicators of acoustic performance. Technical issues

[0003] A related art speaker includes a support member, a diaphragm fixed within the support member for emitting symmetrical ultrasonic waves, and a baffle disposed at intervals on the side of the support member away from the ultrasonic vibration sound-emitting unit. A through-hole is formed through the side of the support member near the baffle, and a narrow gap is formed between the baffle and the support member. The narrow gap is connected to the through-hole. The narrow gap has strong nonlinearity, which causes distortion of the symmetrical ultrasonic waves passing through it, thereby demodulating them into audible sound. However, the efficiency of the diaphragm in demodulating audible sound through the narrow gap is too low, resulting in low amplitude and poor acoustic performance.

[0004] Therefore, it is necessary to provide a MEMS speaker to solve the above technical problems. Technical Solutions

[0005] The object of the present invention is to provide a MEMS loudspeaker with high sound wave demodulation efficiency, good amplitude enhancement effect and excellent acoustic performance.

[0006] In order to achieve the above object, the present invention provides a MEMS speaker, comprising:

[0007] A support structure, comprising a support body and a sound hole extending from one end of the support body to the other end thereof;

[0008] a diaphragm fixed to the inner circumference of the support body and located in the sound hole, the diaphragm being used to emit amplitude-modulated ultrasonic waves;

[0009] An acoustic valve comprises a valve body whose periphery is fixed to the supporting body and located in the acoustic hole, and a variable-section valve hole extending from one end of the valve body to the other end thereof; the variable-section valve hole enables the amplitude-modulated ultrasonic wave passing therethrough to be demodulated into a modulated sound wave.

[0010] Preferably, the inner diameter of the variable-section valve hole changes continuously, so that the bidirectional flow resistance exhibits an asymmetrical effect.

[0011] Preferably, the anisotropic effect of the variable-section valve hole causes the symmetrically amplitude-modulated ultrasonic wave passing through it to become an asymmetric sound wave after exiting, and the asymmetric sound wave includes the modulated sound wave.

[0012] Preferably, the longitudinal and transverse surfaces of the variable-section valve hole are V-shaped structures, and the angle of the V-shaped structure is 1°-89°.

[0013] Preferably, the variable-section valve hole has a multi-layer stepped structure.

[0014] Preferably, the variable-section valve hole is a hole-like structure with an arc-shaped inner wall.

[0015] Preferably, the variable-section valve holes include a plurality of variable-section valve holes, and the plurality of variable-section valve holes are arranged at intervals on the valve body.

[0016] Preferably, the variable-section valve holes include a plurality of variable-section valve holes, which are arranged at intervals on the valve body.

[0017] Preferably, the sound hole, the diaphragm and the acoustic valve include the same plurality respectively; one diaphragm is arranged in each sound hole, and each sound hole is provided with a corresponding acoustic valve.

[0018] Preferably, the variable-section valve body is located in the middle section of the sound hole or at one end of the sound hole.

[0019] Preferably, the inlet and outlet sound axes of the variable-section valve hole are at right angles to the vibration direction of the diaphragm. Beneficial effects

[0020] Compared with the prior art, the MEMS speaker of the present invention is provided with a variable-section valve hole on the valve body that runs through one end to the other end. The variable-section valve hole enables the amplitude-modulated ultrasonic wave passing therethrough to be demodulated into a modulated sound wave, thereby improving the sound wave demodulation efficiency and amplitude of the MEMS speaker, and also improving its acoustic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which:

[0022] FIG1 is a schematic diagram of a first structure of a MEMS speaker provided by an embodiment of the present invention;

[0023] FIG2 is a schematic diagram of a second structure of a MEMS speaker provided by an embodiment of the present invention;

[0024] FIG3 is a schematic diagram of various structures of valve holes provided in an embodiment of the present invention;

[0025] FIG4 is a schematic diagram of a third structure of a MEMS speaker provided in an embodiment of the present invention;

[0026] FIG5 is a schematic diagram of a fourth structure of a MEMS speaker provided in an embodiment of the present invention;

[0027] FIG6 is a schematic diagram of a fifth structure of a MEMS speaker provided in an embodiment of the present invention;

[0028] FIG7 is a cross-sectional view taken along line AA of FIG6 ;

[0029] FIG8 is a diagram of a two-dimensional axisymmetric model of a first structure of a MEMS speaker provided by an embodiment of the present invention;

[0030] FIG9 is an audio waveform diagram of a large-diameter valve hole in the V-shaped structure in FIG8;

[0031] FIG10 is an audio waveform diagram of a small-diameter valve hole in the V-shaped structure in FIG8;

[0032] FIG11 is a structural comparison diagram of a V-shaped valve hole in an embodiment of the present invention and a conventional valve hole;

[0033] FIG12 is an audio waveform diagram of a valve hole with a V-shaped structure and a conventional valve hole structure in an embodiment of the present invention.

[0034] Among them, 100, MEMS speaker; 1, supporting structure; 11, supporting body; 12, sound hole; 13, expansion slot; 2, diaphragm; 3, acoustic valve; 31, valve body; 32, valve hole; 321, main hole; 322, secondary hole. Modes for Carrying Out the Invention

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] An embodiment of the present invention provides a MEMS speaker 100 , which includes a support structure 1 , a diaphragm 2 , and an acoustic valve 3 , as shown in FIG. 1 to FIG. 8 .

[0037] Among them, the supporting structure 1 includes a supporting body 11 and a sound hole 12 extending from one end of the supporting body 11 to the other end thereof; the diaphragm 2 is fixed to the inner circumference of the supporting body 11 and is located in the sound hole 12, and the diaphragm 2 is used to emit amplitude-modulated ultrasonic waves; the acoustic valve 3 includes a valve body 31 whose periphery is fixed to the supporting body 11 and is located in the sound hole 12, and a variable-section valve hole 32 extending from one end of the valve body 31 to the other end thereof; the variable-section valve hole 32 enables the amplitude-modulated ultrasonic waves passing therethrough to be demodulated into modulated sound waves.

[0038] The inner diameter of the variable-section valve hole 32 changes continuously, so that the bidirectional flow resistance presents an unequal effect.

[0039] The non-equivalent effect of the variable-section valve hole 32 causes the symmetrically amplitude-modulated ultrasonic wave passing through it to become an asymmetrical sound wave, which includes a modulated sound wave.

[0040] The inlet and outlet sound axes of the variable-section valve hole 32 are at right angles to the vibration direction of the diaphragm 2 .

[0041] The variable cross-section valve body 32 is located at the middle portion of the sound hole 12 or at one end of the sound hole 12. In this embodiment, the variable cross-section valve body 32 is located at one end of the sound hole 12.

[0042] As an optional embodiment of the design of the variable-section valve hole 32 , as shown in FIG1 , the diameter of the variable-section valve hole 32 at one end close to the diaphragm 2 is larger than the diameter at the other end away from the diaphragm 2 .

[0043] As an optional embodiment of the design of the variable-section valve hole 32 , as shown in FIG2 , the diameter of the variable-section valve hole 32 at the end away from the diaphragm 2 is larger than the diameter at the end close to the diaphragm 2 .

[0044] As shown in Figures 1 and 3, the longitudinal and transverse surfaces of the variable-section valve hole 32 are V-shaped structures, and the angle of the V-shaped structure is 1°-89°; or the variable-section valve hole 32 is a multi-layer step-type structure; or the variable-section valve hole 32 is a hole-like structure with an arc-shaped side wall; or the variable-section valve hole 32 is a hole-like structure with multiple sections of the inner side wall connected end to end and inclined to form a bending line, and the inclination angle of each inclined part increases successively.

[0045] As an optional embodiment of the design of the variable-section valve hole 32 , as shown in FIG. 4 , the variable-section valve hole 32 includes a plurality of variable-section valve holes 32 , and the plurality of variable-section valve holes 32 are spaced apart and arranged in the valve body 31 .

[0046] As an optional embodiment of the MEMS speaker 100, as shown in FIG5 , the acoustic holes 12, diaphragms 2, and acoustic valves 3 each comprise a plurality of the same. A diaphragm 2 is disposed within each acoustic hole 12, and each acoustic hole 12 is provided with a corresponding acoustic valve 3. Preferably, the plurality of acoustic valves 3 are located at the same end of the plurality of acoustic holes 12.

[0047] As an optional embodiment of the MEMS speaker 100, in combination with Figures 6 and 7, the support body 11 is provided with two inwardly recessed expansion slots 13 at one end close to the acoustic valve 3, and the two expansion slots 13 are arranged opposite to each other; the variable-section valve hole 32 includes a main control 321 set through the valve body 31 and two auxiliary holes 322 passing through the side of the valve body 31 to the main control 321, and the two auxiliary holes 322 respectively connect the main control 321 with the two expansion slots 13, and the diameter of one end of the auxiliary hole 322 gradually decreases toward the diameter of the other end.

[0048] The acoustic valve 3 is placed to the side of the diaphragm 2. A coordinating wall is placed at the front sound outlet to guide ultrasonic waves through the valve 3 and then into the outlet. Placing the acoustic valve 3 to the side (or parallel to the diaphragm 2) simplifies the manufacturing process and allows for the design and manufacture of more complex acoustic valves 3 with variable cross-sections, thereby improving demodulation efficiency.

[0049] The principle of the MEMS speaker 100 in this embodiment is shown in FIG8 . Taking the V-shaped variable cross-section valve hole 32 as an example, as shown in Figure 9, a modulated ultrasonic pressure source is applied to the large diameter of the V-shaped variable cross-section valve hole 32. This does not produce audible sound, although the envelope is a low-frequency waveform. As shown in Figure 10, the sound pressure waveform extracted near the small diameter of the V-shaped variable cross-section valve hole 32 has produced obvious asymmetry and contains audible audio information of the audible sound signal.

[0050] The working mechanism of the MEMS speaker 100 in this embodiment is that the diaphragm 2 vibrates, emitting basically symmetrical ultrasonically modulated ultrasonic waves, which pass through the acoustic valve 3 and form asymmetrical ultrasonic waves after exiting, thereby demodulating audible sound. The acoustic valve 3: a variable-section sound channel structure (variable-section valve hole 32), so that the same sound wave signal flows through the sound channel structure from different directions, and the sound waves that exit have obvious differences. For example, when entering from the large-diameter variable-section valve hole 32 with a V-shaped structure, the sound waves have a convergence effect, thereby increasing the sound pressure, while when entering from the small-diameter variable-section valve hole 32, the sound waves are diffused, thereby reducing the sound pressure. The V-shaped variable-section valve hole 32 is a typical acoustic valve 3. The positive and negative pressures of the symmetrical sound waves emitted by the diaphragm 2 pass through the variable-section valve hole 32, and the effects produced are inconsistent, thereby forming asymmetrical sound waves to demodulate audible sound. The V-shaped structure can be set in either direction, but the effects on the positive and negative pressures are reversed.

[0051] As shown in Figures 11 and 12, for ordinary equal-section apertures, symmetrical sound waves remain symmetrical sound waves after passing through, with more changes in the amplitude of the sound. However, the acoustic valve 3 (variable-section valve hole 32) will cause the sound wave to be distorted, resulting in the positive or negative sound wave amplitude being larger than the other side.

[0052] The MEMS speaker 100 of this embodiment is provided with a variable-section valve hole 32 on the valve body 31 that extends from one end thereof to the other end. The variable-section valve hole 32 enables the amplitude-modulated ultrasonic wave passing therethrough to be demodulated into a modulated sound wave, thereby improving the sound wave demodulation efficiency and amplitude of the MEMS speaker 100, and also improving its acoustic performance.

[0053] The above description is only an embodiment of the present invention. It should be pointed out that those skilled in the art can make improvements without departing from the creative concept of the present invention, but these improvements all fall within the scope of protection of the present invention.

Claims

1. A MEMS speaker, characterized in that: The MEMS speaker includes: A support structure, comprising a support body and a sound hole extending from one end of the support body to the other end thereof; a diaphragm fixed to the inner circumference of the support body and located in the sound hole, the diaphragm being used to emit amplitude-modulated ultrasonic waves; An acoustic valve comprises a valve body whose periphery is fixed to the supporting body and located in the acoustic hole, and a variable-section valve hole extending from one end of the valve body to the other end thereof; the variable-section valve hole enables the amplitude-modulated ultrasonic wave passing therethrough to be demodulated into a modulated sound wave.

2. The MEMS speaker according to claim 1, wherein: The inner diameter of the variable-section valve hole changes continuously, so that the bidirectional flow resistance presents an unequal effect.

3. The MEMS speaker according to claim 2, wherein: The anisotropic effect of the variable-section valve hole causes the symmetrically amplitude-modulated ultrasonic wave passing through it to become an asymmetrical sound wave, and the asymmetrical sound wave includes the modulated sound wave.

4. The MEMS speaker according to claim 2, wherein: The longitudinal and transverse surfaces of the variable-section valve hole are V-shaped structures, and the angle of the V-shaped structure is 1°-89°.

5. The MEMS speaker according to claim 2, wherein: The variable cross-section valve hole has a multi-layer stepped structure.

6. The MEMS speaker according to claim 2, wherein: The variable-section valve hole is a hole-shaped structure with an arc-shaped inner wall.

7. The MEMS speaker according to claim 1, wherein: The variable-section valve holes include a plurality of them, and the plurality of variable-section valve holes are arranged at intervals on the valve body.

8. The MEMS speaker according to claim 1, wherein: The sound hole, the diaphragm and the acoustic valve each include a plurality of the same ones; a diaphragm is arranged in each sound hole, and a corresponding acoustic valve is arranged in each sound hole.

9. The MEMS speaker according to claim 1, wherein: The variable-section valve body is located in the middle section of the sound hole or at one end of the sound hole.

10. The MEMS speaker according to claim 1, wherein: The inlet and outlet sound axes of the variable-section valve hole are at right angles to the vibration direction of the diaphragm.

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