| 摘要 |
PROBLEM TO BE SOLVED: To accurately detect the opening of a door, and to make the door automatically returned to a normal state by an inexpensive configuration.SOLUTION: A flip-flop circuit FF1 stores Hi-signals as normal signals, and when a door is opened and a door opening detection switch SW1 is turned on, updates them to Low-signals of a grounded data input terminal. After a switch SW2 is turned on, a power supply voltage V5 is delayed as prescribed by a capacitor C1 and a resistor R4 and applied to a negative terminal of a comparator COM1, and thus, the flip-flop circuit FF1 stores Low for a prescribed time and then stores Hi. An opening determination part 4a of a control part 4 detects that the opening of the door is detected by the Hi-signals stored in the flip-flop circuit FF1 for the prescribed time, and returns it to a normal state thereafter. This invention is applicable to a monitoring system. |
