| 摘要 |
<p>PURPOSE:To widen the range of a load which can be controlled by connecting diodes which are short-circuited by resistances respectively to the cathodes of respective photothyristors and connecting gate resistances between the gate terminals of the photothyristor and the cathodes of the diodes. CONSTITUTION:While a triac 103 is on, the voltage between the T2 and gate terminal of the triac 103 is abut the barrier layer voltage of the p-n junction plus alpha, but when an on current flows through a photothyristor 21 by about 1 mA, a forward voltage drop which is nearly as large as the carrier layer voltage of the p-n junction is generated across a diode 22 connected thereto in series. Consequently, the hold voltage of the photothyristor becomes >=2 times the barrier layer voltage of the p-n junction on condition that the hold voltage is about 1 mA, so resetting is securely performed when the voltage is nearly as high as the voltage between the T2 and gate terminal of the triac 103. The same operation is performed even in the opposite polarity state.</p> |
