| 摘要 |
PURPOSE:To make a device small-sized without containing unnecessary margin in main circuit elements by providing a circuit reducing or prohibiting the load current setting voltage from a load current setting circuit while a load voltage detecting circuit outputs the load voltage detection voltage with the preset value or above. CONSTITUTION:When the detected voltage of a lamp current detecting circuit 9 becomes the preset voltage or above, this device is turned on to ground the output of a lamp current setting circuit 71. At the time of the negative feedback control of the lamp voltage, the lamp voltage is not affected by the lamp current setting voltage, and the control is surely performed only in response to the detected voltage of the lamp current detecting circuit 9. The secondary voltage of an inverter can be set to the minimum required voltage, a choke CH can be made small-sized. |
