Abstract: A light shielding mask 24 opposing to an entrance surface of a fly eye lens 23 is provided, and a transparent portion 25 is made open corresponding to each of lens portions 23b, respectively. Each transparent portion 25 is divided to be formed into a first transparent portion 25a allowing light for forming a projected image 101a on an upper stage of an illuminated surface 100a to enter the lens portions 23b and a second transparent portion 25b allowing light for forming a projected image 101b on an lower stage of the illuminated surface 100b to enter the lens portions 23b, and these are individually set, thereby a difference between an irradiation distance to each of the illuminated surface 100a, 100b due to a step can be complemented, individually.

Abstract: A welding electrode pair of the present invention has substantially columnar first and second welding electrodes coaxially disposed so that their respective tip end faces face each other. Formed on the tip end face of the first welding electrode is a first contact portion protruding therefrom and extending substantially in parallel thereto across the tip end face. Formed on the tip end face of the second welding electrode are second contact portions protruding therefrom substantially in parallel with the tip end face and the first contact portion as if the second contact portions were fit over the first contact portion, extending across the tip end face, and having a substantially circular arc portion at the projected end thereof.