| 摘要 |
PURPOSE:To prevent an erroneous operation operating an external equipment only during a normal connection by feeding a detecting signal of a power source voltage to an extending unit only when a connecting signal of a particular level is transmitted. CONSTITUTION:Under a condition in which an extending substrate REP1 is removed or a signal line 7 is cut, an output of an inverter 9 goes to 'L' level, so that irrespective of a detecting signal LOCK level, an output signal of NOR gate 10 goes to 'L' level, and to respective circuit substrate in an extending unit, a signal of the same level as that when a power source is turned off is given and an operation thereof is stopped. When the extending substrate REP1 is normally connected and a signal line 7 is not cut of, an output of an inverter 9 goes to 'H' level, the detecting signal LOCK is fed to the extending unit as it is and the extending substrate REP1 is brought to an operation condition. |
