| 摘要 |
A control circuit of a direct current servomotor which constantly rotates a floppy disk. A drive pin is connected to a motor shaft of the direct current servomotor, and the floppy disk is driven to rotate at a such state that engagement of the drive pin with a drive hole of the floppy disk chucks up the floppy disk on the servomotor. The direct current servomotor consists of a brushless motor that hall devices detect its magnet pole position and choose among the excited phases of the stator coils. The motor rotates to the reverse direction at the start-up by means of inversion of the input electric current flow to the hall devices in a short while and change-over of the magnet pole detecting direction. The reverse rotation at the motor start-up moves the drive pin on to the rear end of the drive hole, and the subsequent normal rotation firmly starts up the motor. Furthermore, the kinetic energy provided in the run-up period in which the drive pin moves in the drive hole firmly starts up to rotate the floppy disk.
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