| abstract |
Both leg portions (1a), (1b) of a U-shaped bulb (1) are disposed such as to abut against each other or such as to oppose each other with a gap (31) therebetween. The bulb (1) is mounted on an end plate (10) in such a manner that leg ends (1a'), (1b') of the bulb (1) are in contact with the end plate (10), thereby forming an electric discharge passage. If an external force is applied to the bulb (1) in the direction in which the leg portions (1a), (1b) come close to each other, the leg portions (1a), (1b) abut against each other within limits imposed by the range of the elastic deformation of a connecting portion (2a) of the bulb (1), so that breakage of the bulb (1) is prevented. Thus, it is possible to facilitate the manufacture of a low-pressure mercury-vapor arc lamp while reducing the size thereof. |