| 摘要 |
PURPOSE:To prevent a malfunction error caused by chattering and static electricity, by supplying a switch operation detecting signal output from the FF, to the latching circuit, in the switch circuit which is composed of the latching circuit and the FF. CONSTITUTION:When the switch 4 is opened, an output of the NOR circuit 12 of the latching circuit 11 is ''1'', and the ''1'' signal is output from the output terminal Q of the FF5. In this case, the output of the NOR circuit 13 of the circuit 11 is held at ''0'' regardless of the clock phi1 and the output level of the circuit 12. Therefore, the circuit 13 is separated equivalently from the circuit 12, and the circuit 12 operates as an inverter. When a short-width pulse has been generated in the switch 4 by static electricity, etc., it becomes an inverted signal by the circuit 12, but it is not read to the FF5 unless it is generated at the same time as the clock phi2. When the switch 4 is closed, the circuit 12 is inverted to ''0'', and it is read to the FF5, synchronizing with the clock phi2. Even if chattering occurs at the time closing the switch 4, the output of the FF5 holds a state of ''0'' if it ends before rise of the clock phi2. |
