| 摘要 |
PURPOSE:To adjust brightness of a fluorescent lamp well without generating any noise by switching terminals, on the midpoint side where DC power is supplied to respective primary winding divided into two so as to change the number of winding in the appropriate primary winding. CONSTITUTION:The primary winding 2 of a transformer 1 is divided into two at a midpoint while the terminals 16a, 16b, 17a and 17b on the side of the midpoint where DC power 3 is supplied to respective primary windings 2a and 2b divided into two are switched so as to change the number of the primary windings 2 in order to change brightness of a fluorescent lamp 7 connected to the secondary winding 6 of the transformer 1. The terminals on the midpoint side of the primary winding 2 to be supplied with DC power 3 having no voltage fluctuation are switched so as to change over the number of windings of the primary winding 2. Thereby, even when a change-over switch is pulled around, no noise plunges into the circuit of a television picture tube for example by switching. |
