| 摘要 |
One form of a traffic light ( 10, 11 ) employs one or more LED circuits connected to a voltage source (V<SUB>S</SUB>). Each LED circuit includes a series connection of a LED array ( 30 ), a current limiter ( 31 ) and an electronic switch ( 32 ). Each current limiter ( 31 ) controls a flow of LED current (I<SUB>RL</SUB>) through an associated LED array ( 30 ) whenever a switch controller ( 21 ) closes the associated electronic switch ( 32 ). Another form of a traffic light ( 60, 61 ) employs one or more LED circuits connected to a current source (I<SUB>S</SUB>). Each LED circuit includes a parallel connection of a LED array ( 80 ) and an electronic switch ( 81 ). A LED current (I<SUB>RL</SUB>) flows through an LED array ( 80 ) whenever a switch controller ( 71 ) opens the associated electronic switch ( 81 ). |
