| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a discharge bulb which is superior in long distance visibility by being provided with a hot zone in the vicinity of a clear cut off line and is best suited for forming light distribution in which no glaring light is produced. <P>SOLUTION: In the discharging bulb, both end parts of a drum shape ceramics light emitting tube 12 are sealed. An arc tube 11A in which electrodes 15a and 15b are installed facing each other inside the light emitting tube 12 and a sealed space S into which a light emitting substance is sealed with noble gas for starting is provided, is held while being fixed in a state extending forward by an insulating base 30 behind. By providing a light shielding film 50A, at least in a part corresponding to an end edge side seal part 12b in a shrouded glass 20 surrounding the arc tube 11A, the top end part on the side of the horizontal cut off line is made clear in a rectangular light source image projected on a light distribution screen when effective reflecting planes 101a and 101b of a reflector are designed. Therefore, distribution of light which does not produce glaring light can be formed even when the effective reflecting plane 101a is formed so that the light source image projected in the radial direction closely approaches an elbow part so that the hot zone is in the vicinity of the clear cut off line elbow part. <P>COPYRIGHT: (C)2004,JPO&NCIPI |
