| 摘要 |
<p>PURPOSE:To prevent the defects caused by the abnormal voltage, by securing an electric conduction for the switch circuit which forms a discharge line to the input terminal in case the potential of the input terminal is higher than the prescribed level. CONSTITUTION:The transistor T3 is kept on although the writing voltage higher than the critical level arrives at the input line Wj as far as no half-selection writing voltage is applied to the writing terminal. Thus the line Wj is earthed. The transistor T3 is turned off when the voltage is supplied to the writing terminal PR to carry out the writing. The transistor T1 conducts with the transistor T3 turned on when the high voltage more than the sum of the threshold value of the transistors T1 and T3 is induced at the line Wj owing to the effect of the electrostatic field under the unwriting operation. As a result, the transistor T3 discharges the voltage of the line Wj down to the earth level.</p> |
