| 摘要 |
PURPOSE:To obtain a switching device having a good operability by designing the circuit that the changeover is conducted automatically to a next input terminal by skipping an input terminal not connected with an output pin in switching plural inputs sequentially. CONSTITUTION:Suppose that an input terminal 2 is not connected but an input terminal 3 is connected. The leading of a sequential pulse is detected by a logical differentiating circuit 5 and applied to a clock input of an n-adic counter 3. Although an output ''0'' of a binary-decimal decoder 4 is at a high level at first, the state is transited at the trailing of the clock, the decoder output ''1'' goes to high level and the result is given to detection circuits 2 (21-2n). Since the detecting circuits 2 detect whether or not the input is connected and generate a pulse, the generated pulse is applied to a counter clock input of the counter 3 via an OR gete 6, the state is transited, the decoder output ''1'' goes to a low level and the decoder output ''2'' goes to high. The terminals are skipped in this way. |
