| 摘要 |
<p>PURPOSE:To obtain a ballast of an electric-discharge lamp which generates little noise and has a stable electric characteristic, by providing a projecting yoke-holding element in the end portion of the bobbin of a coil so that a silicon steel plate located on the lowermost side of a yoke is prevented from getting on a core. CONSTITUTION:The ballast of an electric-discharge lamp is so constructed that the lowermost side of a yoke 4 is held up by a yoke-holding element 8 provided in the end portion of a coil bobbin 7 put on a core 3, at the joining surfaces of the yoke 4 and the core 3 being opposite to each other. Therefore a silicon steel plate located on the lowermost side of the yoke 4 is prevented from getting on the back of the core 3 even when a pressure A is applied from the lateral side in assembling. The yoke-holding element 8 is so formed that it projects in a little inclination toward the outer periphery of a coil, outside a flange which is positioned outside when the bobbin 7 is fitted on the core 3. The height h2 from the lower end of the flange to the upper end of the yoke- holding element 8 is made to be larger by about 0.5 mm than the height H of the flange of the bobbin 7.</p> |
