| 摘要 |
PURPOSE:To prevent the occurrence of trouble with heating by a method in which the exciting time of a hammer is watched, and excitation exceeding a give time is forcibly prohibited. CONSTITUTION:From a comparator 8, a pulse similar to the pulse of exciting time. The pulse is delayed by an oscillating circuit 10 and a delay circuit 11. The delay time is set in such a way that it becomes longer than the width of the longest time pulse T1 at which excitation is made as in the timing chart. The delay time is also set in such a way that the delay pulse DT1 is trailed before leading of the next exciting pulse T2. The output signal 13 of the delay circuit 11 and the signal 12 showing the exciting pulse are applied to AND gate A. In case where excitation as in abnormal pulse E is made, the output 14 of the AND gate A rises to interrupt the power source + or -Vop. |
