| 摘要 |
<p>PURPOSE:To provide a speed change-over device wherein a frequency dividing circuit and an ''AND'' gate are provided in the speed change-over circuit, and the current passing factor of a motor in which the duty of pulse produced as output from the AND gate has been varied is varied, whereby the speed change-over of the motor becomes possible without requiring the adjustment of the speed change-over of the motor. CONSTITUTION:Whan a saw-tooth wave is supplied as input to an input terminal IN of a discriminating circuit D and a bias voltage Vb determined by resistors R1 and RS is applied to other input terminal T of the circuit D, a pulse signal of a current passing factor of 50% is produced as output from the discriminating circuit D. Upon this occasion, a switch S is turned on to the high speed side, a gate opening signal is added from a power source VE to the input terminal of an ''AND'' circuit A, a signal as shown by (a) is produced as output from the ''AND'' circuit A, and accordingly the motor is operated at a current passing factor of 50%. When the switch S is turned on to the low speed side, a signal from a half frequency dividing circuit F is supplied as output to said circuit A, and a signal of a current passing ratio of 25% as shown by (d) is produced as output.</p> |
