Metal halide lamp, lighting device for metal halide lamp and headlight

Abstract

There are provided a mercury-free metal halide lamp which is improved in light flux rising immediately after starting, more practical and suitable for a headlight, and a metal halide lamp lighting device and a headlight using this. The metal halide lamp according to the present invention comprises: a translucent air-tight container having an inner volume which is not greater than 0.1 cc, including an enclosure portion forming an inner space having a flat surface on a bottom surface, and having a ratio D / L satisfying the following expression: 0.29<= D / L<= 0.43 where D is a distance between the bottom surface and a top surface of the inner space at a central portion in a tube-axis direction, and L is a length of the enclosure portion; a pair of electrodes sealed facing each other with an inter-electrode distance which is not greater than 5 mm; and a discharging medium containing a plurality of metal halogen compounds selected from a group of Sc, Na, In, Zn and a rare-earth metal and a rare gas but intrinsically not containing mercury (Hg), wherein a lamp power per unit inner surface area of the air-tight container is not smaller than 60 (W / cm 2 ).

Description

technical field [0001] The present invention relates to a mercury-free metal halide lamp, a lighting device for a metal halide lamp using the same, and a headlamp. Background technique [0002] There is known a so-called mercury-free metal halide lamp (hereinafter referred to as "mercury-free lamp" for brevity) in which mercury is not substantially enclosed (for example, refer to Patent Document 1). Mercury-free lamps are generally filled with halides of metals such as zinc (Zn) which have a relatively high vapor pressure and are difficult to emit light in the visible region, instead of the conventional mercury enclosed as a buffer substance for forming the lamp voltage. [0003] Mercury-free lamps are expected to be developed as metal halide lamps for headlights of automobiles that are intended to completely eliminate environmental loads. Such a metal halide lamp is required to generate a luminous flux of 80% of the rated luminous flux after 4 seconds of rising the luminou...

AI Technical Summary

Problems solved by technology

However, in mercury-free lamps, since mercury luminescence cannot be obtained, and the high vapor pressure of mercury immediately after lighting cannot be obtained, the evaporation of metal halides is slow, so it is generally difficult to satisfy the above conditions.

Images