| 摘要 |
An active noise control (ANC) system may be implemented to both sides of a fan, such that both directions of the noise emitting are treated to reduce the overall noise. The impact on airflow is minimal, and the technique is very effective in a broad range of low frequencies. Passive sound-absorbing materials may be included for attenuation of high frequencies. The resulting quiet fan produces a low level of noise compared to any other device based on fan, which produces the same capacity of airflow. The quiet fan may be incorporated in any mechanical system which requires airflow induction such as: computers, air conditioners, machines, and more. |
| 主权项 |
1. A quiet fan comprising:
an air-moving device having an inlet side and an outlet side; a first active noise control (ANC) sub-system disposed on the inlet side, the first active noise control sub-system including: a first acoustic transducer; and a first reference acoustic sensor to generate a first reference noise signal corresponding to a first sensed pattern sensed by said first reference acoustic sensor, the first sensed pattern including a first noise pattern from said air-moving device, the first reference acoustic sensor being between the air-moving device and the first acoustic transducer, the first reference acoustic sensor to sense said first sensed pattern prior to the first noise pattern arriving at a location of said first acoustic transducer; a second active noise control (ANC) sub-system disposed on the outlet side, the second active noise control sub-system including: a second acoustic transducer; and a second reference acoustic sensor to generate a second reference noise signal corresponding to a second sensed pattern sensed by said second reference acoustic sensor, the second sensed pattern including a second noise pattern from said air-moving device, the second reference acoustic sensor being between the air-moving device and the second acoustic transducer, the second reference acoustic sensor to sense said second sensed pattern prior to the second noise pattern arriving at a location of said second acoustic transducer; a controller to generate a first control signal to control said first acoustic transducer to generate a first noise destructive pattern, and to generate a second control signal to control said second acoustic transducer to generate a second noise destructive pattern, said controller to generate the first control signal based on a result of subtracting first and second feedback noise estimations from said first reference noise signal, the first and second feedback noise estimations corresponding to said first reference acoustic sensor, the first feedback noise estimation being based on the first control signal and a path between the first acoustic transducer and the first reference acoustic sensor, and the second feedback noise estimation being based on the second control signal and a path between the second acoustic transducer and the first reference acoustic sensor, and said controller to generate said second control signal based on a result of subtracting third and fourth feedback noise estimations from said second reference noise signal, said third and fourth feedback noise estimations corresponding to said second reference acoustic sensor, the third feedback noise estimation being based on the second control signal and a path between the second acoustic transducer and the second reference acoustic sensor, and the fourth feedback noise estimation being based on the first control signal and a path between the first acoustic transducer and the second reference acoustic sensor. |
