BASE ISOLATION DEVICE FOR PRECISION INSTRUMENT

PROBLEM TO BE SOLVED: To elastically fix an instrument and an anchor bolt and to limit the horizontal movement of the instrument while maintaining a buffer function by setting, to zero, the sum of synthetic vectors of a plurality of base isolation members made of cordlike elastic materials for joining an instrument side connecting part and an anchor bolt connecting part. SOLUTION: The instrument side connecting part 4b of a base isolation member 4 is connected so as to be freely rotated around a support leg shaft 2a, and an anchor bolt connecting part 4a is connected so as to be rotated around an anchor bolt 5 buried in a floor structure 3. Here, a direction where the instrument side connecting part 4b is a starting point and the anchor bolt connecting part 4a is a finishing point is set as a vector direction, a spring constant is set to indicate a vector size, and a vector sum is zero. By arranging the base isolation member 4 in such a manner, when an instrument 1 is shifted from an original position, a tensile force is generated in the base isolation member 4 corresponding to its moving direction, and a buffer function is exercised. Thus, the accident of personnel getting stuck in the instrument caused by earthquake shaking is prevented.