ROTOR DETECTOR FOR DC BRUSHLESS MOTOR

PURPOSE:To utilize the differential output of each Hall element pair as a detecting signal by arranging a plurality of Hall elements along the locus of a rotor and forming the Hall element pairs of adjacent Hall elements. CONSTITUTION:Hall elements l, 2, and 3 are respectively used for monitoring W-, V-, and U-phases and arranged symmetrically about the locus of a rotor in the vicinity of the locus. Electric currents are supplied to each Hall element l, 2, and 3 from power lines 8 and 9 for Hall elements. The signals of the W-and Uphase monitoring elements l and 3 are supplied to the W-phase input terminals W+ and W- of a control circuit 4. Since a V-and U-phase signals are supplied to the U-phase input terminals of the circuit 4, the difference signal between the U+ and V+ becomes the U-phase input signal of the circuit 4. Similarly, the W-phase input signal is constituted of the difference signal between the W-and U-phases. The control circuit 4 controls the electric currents supplied to a W-, V-, and U-phase coils 5, 6, and 7 on the basis of these differential signals.