| 摘要 |
PURPOSE:To suppress the heat generation by connecting two pairs of resistive luminous bodies in series for an electric power source and reducing the electric current which flows in a circuit for detecting the breakage to the min. by detecting the breakage state of each resistive luminous body on the basis of the voltage value at the intermediate point of two pairs of resistive heat generating bodies. CONSTITUTION:An illumination circuit for a headlight is equipped with a lighting relay LTR which is intermittently operated according to the ON/OFF state of the contact point of a lighting switch LTS, dimmer relay DMR, and two extinction relays RL1 and RL2 assembled on a circuit base plate CB. Further, a circuit 1 for detecting the breakage of a high beam side filament is installed in a circuit for controlling the extinction lighting of the high beams LH1 and RH1 of the headlight in a twilight state. As for the breakage detecting circuit 1, the conduction of a transistor Tr7 is cut off according to the voltage at the intermediate point (terminal F) of both filaments, when one between two high beam side filaments in series connection is broken, and Tr8 conducts, and a warning lamp WPL comes ON. |
