| 摘要 |
PROBLEM TO BE SOLVED: To provide a weight sensor containing a magnetostrictive element of high detection precision. SOLUTION: A flowing current quantity is increased in a pick-up coil 6 provided to surrounding the magnetostrictive element 2. To attain this, a push- pull circuit is connected to the coil 6 by an H-bridge system. Concretely saying, the first paired transistors 41 are connected to an upper end side of the pick-up coil 6, and the second paired transistors 42 are connected to a lower end part of the coil 6. ON-conditions for the transistor pairs 41, 42 are switched using comparators 43, 44, 45. The pick-up coil 6 is repeatedly charged and discharged alternatively thereby, and a current flows not only in the charge also in the discharge. A variation of an inductance of the pick-up coil 6 to a variation of external force applied to the magnetostrictive element 2 is increased to enhance the detection precision of the weight sensor 1 by increasing the current quantity flowing in the coil 6.
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