| 摘要 |
<p>PURPOSE:To regard a very small leak path as defective and to remove it when the minute leak path is generated between a column line and an earth line, by providing a current supply means which can supply a current from an external terminal to the collector of a PNP transistor TR constituting a PNPN circuit. CONSTITUTION:If a leak path 5 exists between a column line B and the earth line, a base current is supplied to the base of an NPN TR Q1 through a Zener diode DZ, a resistance R1, and a diode DB to activate the whole of the PNPN circuit when a high voltage (10-12V) is applied to an external terminal EXT. When all word drivers 1 and 2 are turned off and a high voltage (15-20V) is applied to an output terminal 4 at this time, a current is flowed to the leak path 5 through the base and the emitter of the NPN TR Q1 and NPN TRs Q2 and Q3. Though the operation of the PNPN circuit cannot be held because this current is very small, NPN TRs Q1-Q3 are turned on as they area because the voltage is applied to the external terminal EXT, and the very small leak current can be observed.</p> |
