| 摘要 |
<p>A single side-sealed metal vapor discharge lamp is disclosed which includes a discharge tube (20) having a sealed section (21) at one end and a discharge region defining envelope (23) at the other end, a pair of metal foils (24, 24) sealed at the sealed section and a pair of electrodes (25, 25), the discharge region of the discharge tube containing a rare gas for starting and a filled gas containing mercury and light emitting metal. The electrodes (25, 25) are each comprised of a rod (26, 26) connected to the metal foil (24, 24) and a coil 27, 27) of at least one turn mounted on the forward end portion of a bent end portion (261, 261) of the rod, the coils being oppositely spaced apart by a predetermined distance in the discharge region (22). The coil (27, 27) is formed of a higher melting point material than a surface material of the forward end portion (261) of the bent portion of the rod (26). With the length from the bent portion (261, 261) to the forward end of the rod (26, 26) indicated by L1, the length of the coil (27, 27) by L2 and the wire diameter of the coil by d, the following inequalities are satisfied: L1 </= 3d and d/2 </= L2 - L1 </= 3d. According to the lamp, it is possible to firmly mount the coil on the corresponding rod (26), to reduce scattering of a material of which the electrode (25, 25) is made, to prevent blackening on the tube wall, to obtain a better starting characteristic and to enhance a lumen maintenance factor.</p> |
