| 摘要 |
PURPOSE:To minimize the influence of change of the inner tube diameter on production process when the inner tube length is changed by making circular the cross section of one end of an inner tube and non-circular that of other part. CONSTITUTION:An inner tube main body 1 is formed in a U-shape and melt- bonded to a stem 3, and the cross section of the tube is made circular. In this electric lamp type fluorescent lamp, when tube length is increased to increase light output, increase in tube voltage is necessary. For example, tube voltage of a lamp having a discharge length of about 260mm., and a tube inner diameter of 12mm. is about 60V. When discharge length is increased to 300mm., tube voltage is increased to 80v at which a lamp is difficult to steadily operate at a power source of 100V. When the major axis is 16mm. and the minor axis is 12mm. and the mean diameter is about 14mm., the tube voltage of the lamp is decreased to about 60V. Other part of discharge pass between electrodes 2 is formed in a circle so that the ratio of the major axis to the minor axis is 1.5 or less without change of the tube diameter of mounting part to the stem 3. Therefore, effective inner diameter of the tube is increased. |
