| 摘要 |
PURPOSE:To turn a thyristor on safely even if a forward voltage is applied while it is in a turn-off period by a method wherein a region having a long life time is provided to n-bases and p-bases of a primary thyristor and an auxiliary thyristor, and the thickness of the p-bases concerned is made smaller than that of other regions. CONSTITUTION:A large number of residual carriers are able to subsist in a region 14 possessed of a long life time in turn-off period. When a forward voltage is applied before a thyristor is turned off, the region 14 is easy to be turned on. A p-type base 4 just under an auxiliary thyristor 10 is especially formed to be small in thickness and high in a sheet resistance, so that the auxiliary thyristor 10 is easy to be forwadly biased. Therefore, at first a re- ignition current 13 flows through an auxiliary emitter 10' and becomes a gate trigger current for a primary thyristor via an auxiliary gate 9. The gate trigger current is possessed of an amplification gate function toward a gate 8. |
