| 摘要 |
PURPOSE:To perform secure current control depending on a pulse width in a simple circuit by improving the linearity of the operation time of a device even in the region wherein the width of the control pulse is small. CONSTITUTION:A control pulse t1 is input to a terminal 3 and amplified. Then, the phase of the pulse is inverted (4), and the pulse is applied to a driver 2 via an NOR circuit 5. At this time, a voltage 6 is generated depending on the current from an electromagnetic valve 1. This potential is given to one terminal of an operation amplifier OP2 by way of a resistor R12 and capacitor C, and a positive potential 10 is given to the output terminal. A reference potential divided at a point P3 is given to the + terminal. At this time, the potential at the point P3 is varied DELTAI by a resistor R15 depending on 2 reference potentials which determin the minimum value I2 and the maximum value I3 of the current of the electromagnetic valve 1. The phase of the output of the operation amplifier OP2 is inverted 12 and is input to the NOR circuit 5. When a circuit 9 which operates depending on the control pulse ti is at a low level, a circuit 8 is turned on, and the counter emf of the electromagnetic vlave 1 is absorbed. The number of the adjusting portions of this curcuit is few, and secure current control depending on the width of the control pulse is performed. |
