| 摘要 |
PURPOSE:To constantly maintain delivery force in spite of variations of temperature, power supply voltage, etc. by feeding back pulsating current, which runs to a electromagnetic coil of an electromagnetic pump, to a control circuit which controls delivery force of the electromagnetic pump after detecting the pulsating current. CONSTITUTION:When a pulsating signal (l) is given to the base of a transistor (Q) via a resistor (R2), pulsating current (lp) having the same pulse shape as that of the pulsating signal (b) runs to an electromagnetic coil (M) of an electromagnetic pump and delivery force of the electromagnetic pump is controlled. Pulsating current (Ip) is detected as terminal voltage of a resistor (R3), averaged by an integration circuit which consists of a resistor (R4) and a condenser (C1), amplified by an operating amplifier (A) which is given a negative feed back by a variable resistor (RV2) and then fed back to a control circuit (CT) via a contact point of a resistor (R1) and a variable resistor (RV1) via a resistor (R5). Therefore, since pulse width decreases even if current value of pulsating current (Ip) increases, pulse area of pulsating current (Ip) does not vary and constant delevery force is maintained. |
