PURPOSE: To enable current detection of high accuracy by reducing the influence of an external magnetic field on an electronic circuit board.
CONSTITUTION: A current detector comprises an electronic circuit board 6 surrounded by the electrical closed loop 9 of a metallic plate. Since the metallic plate forms a closed loop, when downward magnetic flux is applied to the inside of the metallic plate 9, electromagnetic induction occurs and an induction electromotive force is generated in the direction for preventing change in the magnetic flux within the metallic plate 9 and an induced current flows rightwards. Since the magnetic flux within the metallic plate 9 is canceled out, the influence of an external magnetic field on the portion of the electronic circuit board 6 shielded by the metallic plate can be reduced.
HAYASHI SHINICHIRO
SADAMUNE KEIJI
