| 摘要 |
PURPOSE:To preclude malfunction due to an unnecessary signal such as chattering noise by deciding the signal state of an input signal at the time of its resetting from the time continuance when the input signal is inputted. CONSTITUTION:An edge detecting circuit 20 which detects a signal edge is provided and a timer 60 measures specific times T1 and T2 from an edge generated at the change point of the signal. Then, a signal deciding circuit 40 makes an input decision when an optionally applied signal is in the same state for a constant time set by a timer 80 and when the input signal is reset, the input resetting is decided if the reset state continues for a constant time T2; and an inhibiting circuit 80 inhibits the input deciding operation of the signal deciding circuit 40 until an input resetting signal is generated after the output of the input decision signal. Therefore, when a discontinuous signal is superposed upon the signal, the state of the input signal is not generate continuously, so the signal deciding circuit 40 generates no input decision signal. |
