| 摘要 |
<p>PURPOSE:To prevent the dielectric breakdown of an electric discharge lamp to which the output of a direct current step-up transforming circuit is applied through a converter circuit and a current limitting load by stopping the oscillating action of a converter circuit when the electric discharge lamp has been detected to be in an impossible lightening state. CONSTITUTION:A lightening circuit 1 of a metal highland lamp 8 for an automobile is provided with a DC step-up transforming circuit 4, a high-frequency step-up transforming circuit(inverter circuit) 6 which is provided on the rear of the circuit 4 and converts DC voltage into sine-wave AC voltage, and a current limitting load and igniter circuit 7, and a lamp 8 is connected between output terminals of the above circuit 7. In addition to that, whether the lamp has been lightened or not is detected on lamp current, and an igniter starting circuit 9 is provided to send a starting pulse generating signal to the current limitting load and igniter circuit 7 when the lamp has not been lightened. In the case of not lightening, sine-wave oscillation in the high frequency step-up transforming circuit 6 is stopped through a protecting circuit 14, and the generation of a control pulse sent from a control circuit 10 to the DC step-up transforming circuit 4 is also stopped.</p> |
