| 摘要 |
<p>PROBLEM TO BE SOLVED: To control the turning-on/off of a lamp and to adjust the luminous intensity of the lamp by providing high-frequency current with multiple frequencies which are different from one another assigned with control signals different from one another. SOLUTION: When the control of the turning-on/off and the luminous intensity of a lamp is performed, firstly, the direction of the turning-on/off of the lamp 2, the direction of the luminous intensity of the lamp and the address of the subject lamp are input by an operator from an operation console. Next, the input signals are transmitted to each parent station 7 through a central control device, each of the signals is modulated into a high-frequency current in a modem 10 in each of the parent stations 7 and is superimposed on a lamp power-feeding current. At that time, the modem 10 modulates it into a signal having a predetermined intrinsic frequency according to the contents of the control signal and the high-frequency signal current is superimposed over an electric supply line 4 through a power receiving transformer 3 of the parent station 7. Then, the high-frequency signal current is transmitted to each daughter station 8 through the power receiving transformer 3, detected by a detector 11, and thereafter, demodulated to a control signal by the modem 10, and input to a supervisory control circuit 9.</p> |
