| 摘要 |
PURPOSE:To prevent an LED drive current from flowing and achieve a low power consumption when no data signal is input by detecting presence or absence of data signal and then turning on a constant-voltage source at the LED drive portion only when there is data signal. CONSTITUTION:When a data signal is input from a data input terminal 4, input of data is detected by a data signal detection portion 6 and an LED drive portion 2 is switched by a switch 7 so that LED drive current flows constantly. Also the data signal is input to the LED drive portion 2 and one terminal drives an LED 1 of a power supply 5 and then transmits the data signal. On the other hand, when no data signal is input from the data input terminal 4, it is detected that no data is input by the data signal detection portion 6 and the LED drive portion 2 is switched so that no LED drive current flows to the constant power supply source 3 by the switch 7. |
