| 摘要 |
PURPOSE:To prevent the inadvertent signal switching with an electronic device containing an electronic signal switching means, by providing a circuit which inhibits the switching in response to the operation of a selection switch and by means of a control signal. CONSTITUTION:Only one input signal that is selected by the control signal of a control input terminal C of each of switch circuits 14-16 among those input signals supplied to input terminals 11-13 is delivered to a primary signal route 17. A control circuit delivers an H level only to a control output terminal CO selected by switches 24-26 and also supplies an L level to other two output terminals CO. When a switch inhibiting signal is supplied to an input terminal 30, a latch circuit 29 delivers an H level. Then a control circuit 23 is set under a switch inhibiting state via an OR circuit 27 and an AND circuit 28. Then the circuit 23 holds the previous output state by the control signals given from switches 24-26. The inhibition state of the circuit 23 is released by the reset input to be applied to an input terminal 31. |
