PURPOSE: To start a motor smoothly while increasing the rotational speed gradually from zero by operating the output stage with a chopping output having duty corresponding to the difference between a value obtained by integrating the voltage of driving power supply and a value obtained by integrating specific pulse signals generated from the driving power supply.
CONSTITUTION: Upon provision of a driving signal to a power supply circuit 14, a first integrating circuit 15, an oscillation circuit 16, a second integrating circuit 17, and a comparing circuit 18 function and a logic gate 19 or 20 produces a chopping output having such duty as the time interval of high level is initially short and elongates as the integrated voltage from the first integrating circuit 15 increases. This chopping output turns FETQ1, Q2 at first output stage 11 or FETQ3, Q4 at second output stage 12 ON/OFF through transistors Tr3, Tr1, Tr2 or Tr6, Tr4, Tr5.
KATO MASARU
MATSUMOTO YASUKI
