| 摘要 |
PURPOSE:To surely perform starting, lighting and dimming as well as a stop of oscillation in an emergency by providing a circuit for dimming and an emergency detection circuit. CONSTITUTION:At the time of starting a dimming mode of a fluorescent lamp 7, a reset circuit (a) 33 is in operation by a timer circuit (a) 32 so that an emergency detection circuit 34 is made null and the fluorescent lamp 7 gets a state of all output lighting. After the lapse of a fixed time, the circuit (a) 32 stops the operation of the circuit (a) 33, the dimming circuit 31 operates and the lamp 7 is dimmed. At the time of emergency of the lamp 7, when the circuit (a) 33 is stopped after a fixed time by the circuit (a) 32, a signal of the emergency detection circuit 34 is outputted to a stop circuit 35. Then, the oscillation operation of a switching circuit 11 is stopped from a circuit 35 through a driving circuit 30. Further, since the circuit 34 consists of an electron circuit, whose detection level gets variable by changing resistance value of the resistors 53 and 53, repeated ON-OFF and a sure stop of oscillation can be performed regardless of lamp voltage and a surrounding temperature. Furthermore, in a normal lamp a reset circuit makes it possible to surely light while being translated to dimming. |
