Patent ID: 7471496
Filing Date: 2008-12-30
Classification: H01H,H02H

Abstract:
1. A solenoid driving apparatus that drives a solenoid by intermittently supplying an exciting current to the solenoid, comprising: a first current switching element that is turned ON and OFF with a control signal so as to switchably allow and block passage of the exciting current being supplied to the solenoid; a loop current circuit being connected to the first current switching element in which a loop current is caused by stored energy in the solenoid when the supply of the exciting current to the solenoid is stopped by the first current switching element; a second current switching element being disposed between the solenoid and a junction of the first current switching element and the loop current circuit, the second current switching element being directly connected to the junction and being turned ON and OFF so as to switchably allow and block passage of the exciting current and the loop current; a current detector configured to detect a current passing through the solenoid with the second current switching element throughout a period of constant current control for the solenoid; and a control circuit configured to turn the first current switching element ON and OFF intermittently throughout the period of constant current control for the solenoid, according to the current value detected by the current detector, to provide constant current control for the solenoid.