| 摘要 |
PURPOSE:To eliminate the fluctuation of the rotation of an electric motor and improve the quality of a plied thread, by gradually raising a driving voltage for the motor from a prescribed level at prescribed frequency and then increasing the voltage while keeping its level proportional to its frequency. CONSTITUTION:At time t1, a thread-playing machine is started, switches S1, S3, S4 are closed and the output voltage of a variable DC voltage source 33 is amplified by the operational amplifier 37 of a gradient signal generator 200. The amplified voltage is integrated by an integration circuit comprising another operational amplifier 38 and a capacitor C2. The output voltage of the amplifier 38 rises at a speed set by a variable resistor 6. After the time t1, the outout voltage appears as a voltage control signal VS on a terminal 02. When another switch S2 is closed, the output of a variable DC power source 32 is applied to the operational amplifier 35 of another gradient signal generator 100 and processed in the same manner as in the former generator 200. At other time t2, a frequency control signal FS appears on another terminal 01. At still other time t3, the output of another operational amplifier 36 becomes constant and an electric motor is stably driven. |
