Patent ID: 7659670

Claim:
A headlamp control circuit comprising: first and second connecting terminals ( 101 , 102 ) for outputting low-beam lighting voltages that light first and second luminescent parts ( 21 , 31 ) to be used as low-beam headlamps, respectively; third and fourth connecting terminals ( 103 , 104 ) for outputting high-beam lighting voltages that light third and fourth luminescent parts ( 22 , 32 ) to be used as high-beam headlamps, respectively; first and second switch sections (SW 1 , SW 2 ) for turning on and off supplies of said low-beam lighting voltages to said first and second connecting terminals ( 101 , 102 ); a third switch section (SW 3 ) for turning on and off together supplies of said high-beam lighting voltages to said third and fourth connecting terminals ( 103 , 104 ); an output voltage detecting section (D 1 ) for detecting an output voltage on said third switch section (SW 3 ); an indication reception section ( 105 , 106 ) for accepting a low-beam indication that lights said low-beam headlamps ( 21 , 31 ) and a high-beam indication that lights said high-beam headlamps ( 22 , 32 ); and a control section ( 120 ) for turning said third switch section (SW 3 ) to an on-condition in the case where said indication reception section ( 105 , 106 ) accepts said high-beam indication and for turning said first and second switch sections (SW 1 , SW 2 ) to an on-condition in the case where said indication reception section accepts said low-beam indication and in the case where said indication reception section accepts said high-beam indication and said output voltage detecting section (D 1 ) detects no high-beam lighting voltage.