Air-pulse generating device and sound producing method thereof

An air-pulse generating device, comprising:

• a membrane structure and a valve structure;
• a cover structure, wherein a chamber is formed between the membrane structure, the valve structure and the cover structure;
• wherein an air wave vibrating at an operating frequency is formed within the chamber;
• wherein the valve structure is configured to be actuated to perform an open-and-close movement to form at least one opening, the at least one opening connects air inside the chamber with air outside the chamber;
• wherein the open-and-close movement is synchronous with the operating frequency;
• wherein the membrane structure generates a pressure gradient with a pressure-gradient direction within the chamber during an interval;
• wherein the interval is within a half of an operating cycle;
• wherein the operating cycle is a reciprocal of the operating frequency.

An air-pulse generating device, comprising:

• a membrane structure and a valve structure;
• a cover structure, wherein a chamber is formed between the membrane structure, the valve structure and the cover structure;
• wherein an air wave vibrating at an operating frequency is formed within the chamber;
• wherein the valve structure is configured to be actuated to perform an open-and-close movement to form at least one opening, the at least one opening connects air inside the chamber with air outside the chamber;
• wherein the open-and-close movement is synchronous with the operating frequency;
• wherein the membrane structure comprises a membrane portion configured to be actuated to produce a membrane movement with a membrane movement direction;
• wherein a pressure gradient with a pressure gradient direction is produced due to the membrane movement;
• wherein the membrane movement direction and the pressure gradient direction are substantially perpendicular to each other.

A sound producing method, applied in an air-pulse generating device, the method comprising:

• forming an air wave within a chamber, wherein the air wave vibrates at an operating frequency, and the chamber is formed within the air-pulse generating device;
• and
• forming at least one opening on the air-pulse generating device at an opening frequency, wherein the at least one opening connects air inside the chamber with air outside the chamber;
• wherein the opening frequency is synchronous with the operating frequency;
• wherein the step of forming the air wave at the operating frequency comprises:
• forming an amplitude-modulated waveform according to an input audio signal;
• wherein the amplitude-modulated waveform comprises a carrier component with the operating frequency and a modulation component corresponding to the input audio signal.

A sound producing method, applied in an air-pulse generating device, the method comprising:

• forming an air wave within a chamber, wherein the air wave vibrates at an operating frequency, and the chamber is formed within the air-pulse generating device;
• and
• forming at least one opening on the air-pulse generating device at an opening frequency, wherein the at least one opening connects air inside the chamber with air outside the chamber;
• wherein the opening frequency is synchronous with the operating frequency;
• wherein the air-pulse generating device comprises a membrane structure, and the step of forming the air wave at the operating frequency comprises:
• generating a pressure gradient with a pressure-gradient direction, via the membrane structure, within the chamber;
• wherein the pressure-gradient direction of the pressure gradient generated by the membrane structure is substantially parallel to the membrane structure.

A sound producing method, applied in an air-pulse generating device, the method comprising:

• forming an air wave within a chamber, wherein the air wave vibrates at an operating frequency, and the chamber is formed within the air-pulse generating device;
• and
• forming at least one opening on the air-pulse generating device at an opening frequency, wherein the at least one opening connects air inside the chamber with air outside the chamber;
• wherein the opening frequency is synchronous with the operating frequency;
• wherein the air-pulse generating device comprises a membrane structure, and the step of forming the air wave at the operating frequency comprises:
• actuating a membrane structure to produce a membrane movement with a membrane movement direction, such that a pressure gradient is formed;
• wherein the pressure gradient with a pressure gradient direction is produced due to the membrane movement;
• wherein the membrane movement direction and a pressure gradient direction are substantially perpendicular to each other.