| 摘要 |
PURPOSE:To enhance reliability and to realize cost reduction by grounding at least one of m-phase windings through a semiconductor element. CONSTITUTION:When a power supply voltage Vcc is being fed to a driving circuit 1, the driving circuit 1 feeds an AC three-phase current to a spindle motor 3 upon switching of a control signal CE from 'H' to 'L' to start rotation of the spindle motor 3 which subsequently reaches a predetermined rotational speed. When the power supply voltage Vcc is interrupted, a transistor 2A is turned ON and phase W winding of the spindle motor 3 is grounded to produce a ground current(brake current) and thereby the spindle motor 3 enters into generative brake state resulting in reduction of rotational speed. Consequently, reliability of circuit is enhanced resulting in an inexpensive circuit. |
