JPS54107712A - Transport mechanism of magnetic tape of portable microminiature tape recorder - Google Patents

Abstract

PURPOSE:To transport magnetic tape at a specified speed with stability by providing a synchronous motor consisting of a moving magnetic rotor having 3 pairs of symmetrical magnetic poles and a closed magnetic path yoke containing a pair of internally opposing protrusions. CONSTITUTION:A pair of internally opposing protrusions 4A, 4B facing the inner side are provided to a protruding yoke 1A in the position symmetrical to the revolving shaft of a rotor 3 composed of permanent magnet and likewise a pair of relatively narrow magnetic paths 5A, 5B are provided near these. Further, a driving coil 6 is wound to the coil yoke 1B. When the yoke 1 is excited like the solid line arrows shown in A, N-N poles and S-S poles repulse with each other and the rotor 3 generates rotating torque like the briken lines. And the rotor stabilizes in the position shown in B but the yoke 1 is immediately excited in the opposite direction by the excitation of alternating currents and again by the repulsion action of the same poles with themselves the rotating torque is produced and is applied and this cycle of alternating currents is controlled at the rotating speed at which the 1/3 rotation of the rotor 3 accurately coincides, thus the rotation is continued.