Air-pulse generating device with tooth edge patterned slit
An air-pulse generating device includes a film structure including a first flap and a second flap opposite to each other. The film structure is actuated to operate at an ultrasonic frequency, and the air-pulse generating device produces a plurality of air pulses at an ultrasonic pulse rate. The first flap and the second flap are actuated to perform a differential movement to form an opening or a virtual valve. A slit is formed between the first flap and the second flap, and the opening or the virtual valve is formed because of the slit. The slit is formed as a zigzagging pattern on the film structure.
1. An air-pulse generating device, comprising:
a film structure, comprising a first flap and a second flap opposite to each other;
wherein the film structure is actuated to operate at an ultrasonic frequency, and the air-pulse generating device produces a plurality of air pulses at an ultrasonic pulse rate;
wherein the first flap and the second flap are actuated to perform a differential movement to form an opening or a virtual valve;
wherein a slit is formed between the first flap and the second flap, and the opening or the virtual valve is formed because of the slit;
wherein the slit is formed as a zigzagging pattern on the film structure;
wherein the slit zigzags in a back-and-forth manner among a first direction and extends toward a second direction.
2. The air-pulse generating device of claim 1 ,
wherein the slit comprises nonzero projection onto the first direction.
3. The air-pulse generating device of claim 1 ,
wherein the first flap comprises a plurality first protrusions and the second flap comprises a plurality second protrusions;
wherein the first protrusions and the second protrusions are interleaved with each other.
4. The air-pulse generating device of claim 3 ,
wherein the first flap comprises a plurality first depressions and the second flap comprises a plurality second depressions;
wherein the first protrusions and the first depressions are interleaved with each other.
5. The air-pulse generating device of claim 1 ,
wherein the first flap comprises a plurality first protrusions;
wherein a protrusion among the first protrusions comprises a plateau portion.
6. The air-pulse generating device of claim 1 ,
wherein the first flap comprises a plurality first protrusions;
wherein a protrusion among the first protrusions corresponds to a width;
wherein the width is greater than a height of walls between the first flap and the second flap.
7. The air-pulse generating device of claim 1 ,
wherein the first flap comprises a plurality first protrusions;
wherein a protrusion among the first protrusions corresponds to a width;
wherein the width is greater than a displacement difference between free ends of the first flap and the second flap when the virtual valve is opened.
8. The air-pulse generating device of claim 1 ,
wherein the first flap comprises a plurality first protrusions;
wherein a protrusion among the first protrusions corresponds to a depth;
wherein the depth is greater than 15% of an anchor-to-anchor distance.
9. The air-pulse generating device of claim 1 , wherein the slit forms a tooth edge pattern.
10. The air-pulse generating device of claim 1 , wherein the slit forms a rectangular tooth edge pattern.
11. The air-pulse generating device of claim 1 , wherein the slit forms a trapezoid tooth edge pattern.
12. The air-pulse generating device of claim 1 ,
wherein the film structure is actuated to perform a common mode movement to form an amplitude-modulated ultrasonic air pressure variation with an ultrasonic frequency.
13. The air-pulse generating device of claim 12 ,
wherein the first flap and the second flap are actuated to perform the common mode movement and the differential movement simultaneously.
14. The air-pulse generating device of claim 1 ,
wherein the first flap and the second flap are actuated to perform the differential movement, so as to form the opening at an ultrasonic opening rate.
15. The air-pulse generating device of claim 1 ,
wherein the virtual valve is in a closed state when a difference of displacement of the first and second flaps is less than a thickness of the film structure;
wherein the closed state of the virtual valve occurs at transitions of the differential movement of the first flap and the second flap.
16. The air-pulse generating device of claim 1 ,
wherein the slit zigzags on the film structure such that an area coverage ratio is no smaller than 0.25.
17. The air-pulse generating device of claim 1 ,
wherein the slit zigzags on the film structure such that a displacement coverage ratio is no smaller than 0.5.
18. The air-pulse generating device of claim 1 ,
wherein the first and second flaps form a flap pair;
wherein a time of the virtual valve being closed is aligned to a time corresponding to a common mode movement of the flap pair toward a third direction;
wherein a time of the virtual valve being opened is aligned to a time corresponding to the common mode movement of the flap pair toward a fourth direction opposite to the third direction.
19. The air-pulse generating device of claim 1 , comprising:
a covering structure;
wherein a chamber is formed between the film structure and the covering structure.
20. The air-pulse generating device of claim 19 ,
wherein an orifice is formed on the covering structure;
wherein the plurality of air pulse propagates outward via the orifice.
21. The air-pulse generating device of claim 1 ,
wherein the first and second flaps form a flap pair;
wherein a time of the virtual valve being closed is aligned to a time corresponding to a peak acceleration of a common mode movement of the flap pair.
22. The air-pulse generating device of claim 1 ,
wherein a combined common mode displacement corresponding to the virtual valve is evenly distributed within a range between a rightmost free end of the first flap and a leftmost free end of the second flap.
23. The air-pulse generating device of claim 1 ,
wherein an acoustic impedance corresponding to the virtual valve is evenly distributed within a range between a leftmost free end of the second flap and a rightmost free end of the first flap.
24. The air-pulse generating device of claim 1 , wherein the air-pulse generating device is applied in a sound producing application.
25. The air-pulse generating device of claim 1 , wherein the air-pulse generating device is applied in an air movement application.