1. Field of the Invention
The present invention relates to a technology for reducing a starting time of the discharge lamp for high beam.
2. Background of the Invention
A known lighting circuit of a discharge lamp(e.g. a metal halide lamp)for a vehicle comprises a DC power circuit, a DC-to-AC converter, and a starting circuit (a starter circuit).
If a plurality of discharge lamps is used as a light source for a vehicle, a means for controlling the lamps is required. For example, when a discharge lamp is used as a front light of an automobile, and a high beam and a low beam are separately provided by an individual discharge lamp(so-called, four-lamp lighting), a pair of discharge lamps is required on the right and the left sides of the vehicle. Each pair of the discharge lamps requires a lighting circuit for controlling the lamp.
However, if a discharge lamp for high beam and a discharge lamp for low beam in a conventional device have the same power rating, meaning both discharge lamps are lighted with the same electrical power, the discharge lamp for high beam may not be able to attain a luminosity required for a condition that momentarily requires a certain amount of brightness. For example, the condition may be signaling to pass by turning the headlights on and off (on/off).
An object of the invention is to secure a quantity of illuminating light necessary for a vehicle by momentarily raising the luminous flux of the discharge lamp for high beam.
A discharge lamp device for a vehicle according to an implementation of the invention comprises a discharge lamp for high beam, a discharge lamp for low beam, both having the same power rating, and a lighting circuit for controlling those lamps. The lighting circuit controls the lamps in such a way that in lighting the lamps, the electrical power supplied for lighting the discharge lamp for high beam is made greater than the electrical power supplied for lighting the discharge lamp for low beam.
Therefore, according to an implementation of the invention, by controlling the electrical power for lighting the discharge lamp for high beam to be greater than the electrical power for lighting the discharge lamp for low beam, the implementation achieves to raise momentarily the luminous flux of the discharge lamp for high beam.