| 摘要 |
PURPOSE: To control lamp voltage by applying a voltage lower than that applied during ignition to the filaments of a fluorescent lamp at an initial preheating stage, increasing the voltage gradually to high voltage values unit the lamp is ignited, and lowering the voltage in response to an increased load after the lamp is ignited. CONSTITUTION: During the initial energization and operation of a controller 10, an operating voltage is supplied to a control circuit 36 from a power circuit 40 via a line 39. A voltage generated at a start line 44 does not apply a sufficiently great voltage to ignite lamps in a preheating stage, but supplies a high frequency current to the filaments of the lamps 11, 12. In a subsequent ignition stage, the lamp voltage increases gradually to a high voltage value until the lamps are ignited, and, when the lamps 11, 12 are ignited, the lamp voltage decreases in response to increased load due to the conduction of the lamps. Therefore, a fluorescent lamp control circuit and a dimming control part control luminosity accurately and safely over a wide range. |
