| 摘要 |
PURPOSE:To make the control of smooth rotation of a brushless motor possible by providing a motor drive with a drive signal control means that carries out a closed loop control of a changeover timing of exciting current for the brushless motor on the basis of an detecting signal from a rotation position detecting means. CONSTITUTION:A current changeover circuit 2 aims at carrying out a closed loop control of a changeover timing of coil exciting current for a motor 6 in response to a detection output pulse 50 from an encoder 16. For this purpose, a current changeover circuit 2 has a counter circuit 51, comparator circuit 52, decoder circuit 53, signal select circuit 54, and start/stop circuit 55. The comparator circuit 52 consists of a latch 70 and comparator 72. Here, in the latch 70 a counter comparison value is set by a comparison value setting signal 34, while the comparator 72 compares a counter value with latch data and generates an excitation changeover signal when both the counter value coincides with latch data. |
