| 摘要 |
PURPOSE:To control suitably against noise and vibration by inputting a signal synchronized with the rotating speed of a cross flow fan to an adaptive filter composed of a digital signal processor, forming a signal having a correlation to a kNz sound, and reducing k to Nz sound by a surface vibration of a piezoelectric element adhered to a stabilizer. CONSTITUTION:A signal corresponding to the harmonic wave of a kNz sound by a frequency divider from a signal synchronized with a cross flow fan 1. A harmonic wave such as a sine wave, etc., of kNz (Hz) is formed by a waveform generator 18 from the signal. An adaptive filter 5 composed of a digital signal processor controls the output of a noise monitoring microphone 9, regulates the surface vibration of a piezoelectric element so that the output of the microphone 9 becomes minimum, i.e., automatically controls a phase, an amplitude, a delay time, etc. Accordingly, a generation source of the kNz sound itself generated by exciting a vibration near the end of a stabilizer by the flow of the fan is interrupted to suppress extension of noise power in a three-dimensional space. |
