BURGLAR MONITORING SYSTEM AND MONITOR CAMERA AND CONTROL UNIT USED IN THE SAME

摘要

PROBLEM TO BE SOLVED: To supply a power source in an optimum state to a monitor camera providing a speaker. ;SOLUTION: Unless the microphone 33 of a control unit 20 is used, a constant current circuit 22 superimposes prescribed first D.C. current on a co-axial cable 40 so as to supply it to the monitor camera 1. When the microphone 33 is used, a monitoring person depresses a microphone switch 34. Thus, the switch 31 is closed, the switch 26 is opened and the constant current circuit 22 generates prescribed second D.C. current so as to superimpose it on the co-axial cable 40. At this time, current detection 16 detects that prescribed second D.C. current is supplied so that the switch 9 is opened and the switch 13 is closed. Thus, voice spoken with the microphone 33 is FM-modulated in a modulating part 30, transmitted by the co-axial cable 40, demodulated by the demodulating part 12 of the monitor camera 1 and issued from the speaker 10.;COPYRIGHT: (C)1997,JPO