| 摘要 |
PROBLEM TO BE SOLVED: To prevent lowering in heat radiating effect by avoiding the effects of radiant heat of a fluorescent lamp. SOLUTION: Switching elements Q1 to Q3 , each equipped with a heat sink 4 as well as choke coils L1 to L3 are mounted, as large-sized heating component on a substantially circular arc-shaped printed circuit board 3. Among these large-sized components, the switching elements Q1 to Q3 and the choke coil L2 disposed on a peripheral part 1b of a case 1 are disposed and mounted, such that the longitudinal directions of the heat sinks 4 and the longitudinal direction of the choke coil L2 substantially coincide with diametrical directions of the printed circuit board 3. Accordingly, the surfaces of the heat sinks 4 contributive to radiation (surfaces running along the longitudinal direction) and a surface of the choke coil L2 contributive to heat radiation (an opened surface of a core in the longitudinal direction) will not face the case 1 and are hardly affected by radiant heat from fluorescent lamps 21 , 22 , so that lowering in heat radiating effect can be prevented. |
