| 摘要 |
PURPOSE:To operate the other terminal of a branch signal line without being influenced by short circuit, by disconnecting a controlling circuit in a branching device, in case short circuit has occurred in one terminal side of the branch signal line. CONSTITUTION:A main device 1 is connected to a branching device 2 by signal lines (a), (b), and the device 2 is connected to terminal circuits 3-6, 7-10 by signal lines (c), (d) and (e), (f), respectively. For instance, when a signal (d) and a grounding circuit GND2 are short-circuited, charged voltage of a capacitor C1 is discharged by a resistance R6, the capacitor C1 , the line (d), and a closed circuit of the circuit GND2. Accordingly, the potential of a point G of a transistor TR4 becomes zero potential from negative by time constants of the resistance R6 and the capacitor C1 after the short circuit. Also, as for the positive potential of an electric power supply PS, the voltage drops by a resistance R7, a current is made to flow in the DS direction of the TR4, and a pole D is set to zero potential. As a result, the collector and the emitter of a TR3 are disconnected, therefore, the signal (f) is transmitted to the main device 1 through the signal line (b). |
