| 摘要 |
PURPOSE:To prevent a driving coil from being burned when an excessively large electric current passes through, by allowing an excess current to pass a fusing fuse when a driving transistor, to which a driving signal is not put in, is in current-ON condition. CONSTITUTION:For instance, in the case of occurrence of such a situation that due to a trouble on a driving transistor QA2, collector side of a driving coil SL2 became in grounding condition, and therefore, driving current ID2 is passing the driving coil SL2 in spite of the fact that a driving signal DS2 is LOW, a potential difference detecting signal VS2 becomes HIGH, and at the same time, the driving signal DS2 is inversed by an inverter NOT2 to become HIGH, an AND gate AND2 is operated, a detecting signal SS2 is put out to an OR gate OR so that an output signal of the OR gate becomes HIGH, and at the same time, the gate of a thyrister SCR is impressed with voltage. By a series of these operations, when electric current passes the thyrister SCR, an excessively large current passes a fuse 1 to fuse it, and therefore, the driving coil SL2 is prevented from being burned. |
