This creation provides a cold cathode ultraviolet lamp that enhances the ON/OFF characteristics. The welded glass beads 15a are welded to the inner surface of the glass tube, and the inner surface of the end portion of the glass tube is present outside the welded glass beads 15a. The length L of the welded glass beads 15a is L = 1.5 to 3.5 mm, the diameter D of the sealing pin 13a is D = 0.65 to 0.95 mm, and the width W of the welded glass beads 15a perpendicular to the axial direction of the glass tube is 2.55 to 3.05. In the case of mm, the time constant τ of the glass frit 15a and the frit glass of the glass tube becomes small, and the on/off characteristics of the cold cathode ultraviolet lamp 1 are improved.本創作提供一種提昇導通（ON）／斷開（OFF）特性之冷陰極紫外線燈。熔接玻璃珠15a將封堵銷13a與玻璃管的內面加以熔接，且熔接玻璃珠15a的外側存在有玻璃管的端部的內面。於熔接玻璃珠15a的長度L係L＝1.5～3.5mm、封堵銷13a的直徑D係D＝0.65～0.95mm、熔接玻璃珠15a之垂直於玻璃管的軸向的寬度W係2.55～3.05mm時，則熔接玻璃珠15a及玻璃管的熔接玻璃的時間常數τ變小，提昇冷陰極紫外線燈1的導通／斷開特性。
