| 摘要 |
PURPOSE:To obtain an economical effect and miniaturize the whole body by providing the function optionally controlling the DC current so that the set value of the DC current is inversely proportional to the DC voltage. CONSTITUTION:When the output DC voltage of a DC power source section is changed, a current set value signal with the value inversely proportional to the DC voltage changed by a setting means 2 is outputted. The detected current value of the output current of the DC power source section is corrected to coincide with the current set value signal inputted from the setting means 2 to obtain the current signal inversely proportional to the DC voltage correctly by a current control means 7. This current signal is deviation-amplified by a pulse width modulating circuit 11 to be pulse width-modulated, a driving circuit 12 drives an inverter 13 while using this output as a control signal, and a discharge type light emitting tube is lighted by the high-frequency output of the inverter 13. Constant electric power can be invariably fed to the discharge type light emitting tube without providing an expensive AC voltage stabilizer. The cost is reduced, and the whole device can be miniaturized. |
