| 摘要 |
PROBLEM TO BE SOLVED: To reduce cost by eliminating the necessity of arranging a level shift circuit between a control part and a driving part. SOLUTION: An output current detecting part 8 composed of a resistor element is connected between one output end (an output end on a low potential side) of a convertor 3 and an input end on a ground side of an invertor 4, and a connection point between the input end on the ground side of the invertor 4 and the detecting part 8 is connected to an output end (a negative electrode) on a ground side of a DC power source 1. Accordingly, since potentials of signal ground of a control part 9 and a ground potential of a driving part 5 do not rise even if an output current (a lamp current) flows into the detecting part 8 and a voltage drop V<SB>R</SB>occurs, the driving part 5 does not operates erroneously even if a signal voltage to be output from the control part 9 to the driving part 5 is set to a low value (e.g., 5 V), and a conventional level sift circuit 10 can be omitted and the cost can be reduced. COPYRIGHT: (C)2005,JPO&NCIPI |
