| 摘要 |
PURPOSE:To decrease the coolest temperature of an outer tube and improve lamp efficiency by coating the partial area among the inner surface of the outer tube, the outer surface of an inner tube, and the inner surface of the inner tube with a material that is transparent to visible light and is reflective to infrared rays of 2mum or more. CONSTITUTION:An outer tube 1 forms a spherical or cylindrical airtight container and seals low pressure mercury vapor inside. An inner tube 2 is normally composed of two U-shaped tubes. A single electrode 3 is mounted and sealed on each of one end and each of the other end is formed by being opened in the outer tube 1. Discharge passes through the inner tube 2 from the single electrode 3, jets out in the outer tube 1, passes through the inner tube 2 again, and reaches the other electrode 3. In addition, the partial area of at least one surface among the inner surface of the outer tube 1, the outer surface of the inner tube 2 and the inner surface of the inner tube 2 is coated with a tin oxide coat 4 that is transparent to visible rays and is provided with reflecting characteristics for infrared rays in a wavelength region of at least 2mum or more. As a result, the coolest section temperature of the outer a tube wall can effectively be decreased and lamp efficiency can always be kept high. |
