| 摘要 |
<p>PURPOSE: To reduce the number of wires necessary for connecting an opening point and a central monitoring unit and reduce the total length of the wires used therefor, in monitoring the closure of the opening point of a vehicle. CONSTITUTION: A central unit 1 is connected with all opening points to be monitored by a single common line with two conductors 31, 32, and provided with at least one periodic signal generator 28 connected with the two conductors, and each opening point 2, 4 is provided with resonance circuits 17, 18 tuned to the frequency of the periodic signal generated by the periodic signal generator 28 of the central unit 1. The resonance circuits 17, 18 are connected with closure contacts 19 of the opening points, and a device is provided with an abnormality signal generating means, capable of responding to change of the signal generated from the periodic signal generator 28, in response to the corresponding closure contact 19.</p> |
