| 摘要 |
PURPOSE:To decrease the amount of a phosphor used in making a straight- tubular fluorescent lamp having a length of 1,650+ or -30mm. so as to reduce its cost by decreasing the diameter of the lamp to within a specified range. CONSTITUTION:The tube length and the tube diameter of a straight-tubular fluorescent lamp charged with a gas consisting of argon at a pressure of 1.0-3.5 Torr, are adjusted to 1,650+ or -30mm. and 25.5+ or -2.5mm. respectively. During the ignition in a commercial frequency, this lamp has a current of 250+ or -50mA and an electric power of 30-44W. By thus adjusting the diameter of the lamp to that of a straight-tubular fluorescent lamp of a rank lower by one, it is possible to decrease the amount of a phosphor used. This is advantageous in terms of the cost of the lamp. When a lamp is ignited with the same current as that for a one rank higher lamp, there is a general tendency that the temperature of the tube wall excessively increases resulting in a decreased brightness and that the lamp efficiency at around 25 deg.C is deteriorated. However, with the lamp of this invention, it is possible to increase the lamp efficiency while reducing the cost. |
