抄録
This paper deals with an active acoustic enclosure for preventing vibration of precision measuring equipment, e. g. Scanning Probe Microscope (SPM) and Scanning Electron Microscope (SEM) etc., due to surrounding sound noise. The authors have investigated the active sound transmission control and have proposed the effective actuation method using point force actuators and the practical sensing method of the volume velocity of the panel using piezoelectric film sensors. Moreover, the acoustic enclosure using the proposed active sound transmission control method has been developed. This study experimentally investigates the sound insulation property of the prototype active acoustic enclosure for Atomic Force Microscope (AFM), which is a type of the SPM. The performance is affected by the control methods, the structure of the enclosure and the surrounding sound field where the enclosure is installed. The experimental results in the case of using flat panels and honeycomb panels, in the case of some surrounding sound fields and in the case of using two type of control methods (Single Input Single Output (SISO) control and Multi Input Single Output (MISO) control), etc. are shown. Then, the influences of these parameters are discussed in order to improve the insulation property of the enclosure. It is found that by using honeycomb panels, MISO control and acoustic treatment in the enclosure and installation site, the greater control effect can be obtained in the low frequency range and as a result weight saving can be achieved.
