| 摘要 |
PROBLEM TO BE SOLVED: To make a mechanism thinner by reducing the mutual vibration margin between first and second movable bases while allowing frequencies generating maximum amplitudes to be shifted by making primary resonance frequencies of first and second vibration isolation members respectively supporting the first and second movable bases differ. SOLUTION: First and second movable bases 1, 21 are respectively provided with spindle motors rotatingly driving first and second disks 11 and read out signals recorded on the first and second disks 11. A first fixing base 4 is provided with first vibration isolation members 9 consisting of viscoelastic bodies of rubber or the like and viscous fluid of silicon oil or the like, which suspend four corners of the movable base 1. A second movable base 21 is arranged at the underside of the base 1 and four corners of the base 21 are suspended with respect to a second fixing base 24 with second vibration isolation members 25 consisting of rubber material having large internal losses. Attenuation curves of the first and second vibration isolation members 9, 25 are set so that primary resonance frequencies of the members 9, 25 respectively become 20, 50 Hz.
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