| 摘要 |
PURPOSE:To maintain the coolest point of a lamp more stably and reduce the variance of the lamp voltage and color tone by providing an expanded inner wall surface having a limited angle against the axial direction of a discharging electrode from the inner edge of the seal hole of the discharging electrode. CONSTITUTION:An expanded inner wall surface 6 having an angle theta1 of 60 deg.- 90 deg. against the axial direction of the electrode, i.e., the axial direction of a ceramic luminous tube from the inner edge of a seal hole 5 is formed. In addition, an expanded inner wall surface 7 having an angle theta2 smaller than the angle theta1 is formed between the expanded inner wall surface 6 and a luminous inner wall surface 8. |
