| 摘要 |
PURPOSE:To restrain a temperature rise in the vicinity of an electrode by changing the style of control to constant electric power control when a lighting condition is transferred to a cold cathode mode from a hot cathode mode. CONSTITUTION:An electrode having performance of both a hot cathode and a cold cathode is provided, and a small fluorescent lamp 12 of which a single lamp is lighted in equal to or less than LOW is lighted by electric power supplied from an inverter circuit 11. Since there exists an electric current detecting circuit 14 on the primary side of the inverter circuit 11, a switching element SW is driven by a control circuit 15 so as not become equal to or larger than a preset upper limit value. Thereby, even if a primary side electric current is increased when a lighting condition is changed to a cold cathode mode from a hot cathode mode, electric power to light the small fluorescent lamp does not become equal to or larger than a constant value. |
