| 摘要 |
PURPOSE:To provide an impact head driving circuit constituted so as to prevent the damage of a drive element. CONSTITUTION:The OFF-timing of a transistor Q1 is detected by a drive element OFF-timing detecting means 100 and a turn-OFF time being the time before the transistor Q1 changes from an 0N-state to an OFFstate by turning an input signal OFF is measured by an ON/OFF state change time measuring means 110. When the measured turn-OFF time becomes larger than the value of a predetermined turn-OFF time converted to temp. tjLIM wherein a margin is provided to the junction temp. rated value tjMAX of a drive element, a protective circuit 120 prevents that the transistor Q1 is turned ON and generates an alarm signal ALM to protect a circuit. |
