| 摘要 |
PURPOSE:To increase brightness toward a sealing part as well as to make a light distribution characteristic uniformizable, by forming the thickness of a light emitting tube so as to make it thicker in a part proximate to the sealing part than the main part. CONSTITUTION:A light emitting tube 1 is constituted so as to be different in thickness distribution of the circumference of a light emitting space. That is to say, the thickness t1 of a main part of the light emitting tube 1 is set down to a range of 0.3mm.-1.5mm., while at the same time, at least a part among adjacent parts 14 of sealing parts 5 and 5 of the tube 1, namely, the thickness of a boundary part with these sealing parts 5 and 5 is made to be larger than the thickness t1 of the main part 13, and when the maximum value is set down to tmm., it is made so as to be in a range of t/t1=1.4-3.3 and simultaneously, over against the thickness t2 of each of sealing parts 5 and 5, it is constituted so as to become t/t2=0.5-1.3 like this. With this constitution, refraction of light is produced in a direction where thickness is large and thereby a quantity of light toward these sealing parts is increased, while a loss of light due to these sealing parts is well reducible. |
