| 摘要 |
PURPOSE:To detect disconnection positively by setting the terminal voltage of resistance in one set of system in a light source circuit of a lighting body formed of scores of' parallel-connected sets of systems, as the reference voltage, and batch-connecting the other remaining sets of systems to shunt resistance to compare the voltage of two resistances with each other. CONSTITUTION:This lighting body 10 is formed of a light source circuit formed by parallel-connecting scores (N pieces) of sets of systems, each of which is formed by series-connecting plural LED elements. The terminal voltage of current limiting resistance VR in No.N sets of systems, for instance, is made the reference voltage, while systems provided with the current limiting resistances R1-RN-1 in the remaining No.1-No.N-1 sets of systems are batch- connected to a current detecting shunt resistance 11. When either LED element in No.1.-No.N-1 sets of systems is disconnected, both end voltage of the shunt resistance 11 is lowered, and the state of the output of a first comparator 12 becoming the high level is judged by a logical circuit 13 to perform the detection of disconnection. |
