| 摘要 |
PURPOSE: To measure a magnetic field while protecting an element against damage even under radiation by placing a movable coil in a magnetic field to be measured and measuring the electromagnetic force induced by feeding a current. CONSTITUTION: A movable coil 1 is connected with a current source 2 and fed with a constant current I. Consequently, an electromagnetic force (F=IBL) acts at the opposite ends of the movable coil 1 having a length L of one side in the center of field of flux density B and the coil 1 begins to turn about a rotary shaft 3. A mechanical force (tensile/compressive force) is thereby applied to the resistance wire 5 in a load sensor 4 fixed to the coil. The resistance wire 5 elongates/contracts in proportion to the electromagnetic force (load) F because of the resiliency thereof and a formula F=k.ΔR is satisfied between the variation of resistanceΔR and the electromagnetic force F, where (k) is a proportional constant. When a Wheatstone bridge is constituted using the resistance lines at the time of measuring variation of resistance, an output voltage proportional toΔR can be obtained. Since no integrator is employed and the movable coil is not made of a semiconductor, the field can be measured accurately even under radiation.
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