| 摘要 |
PURPOSE:To prevent the brightness of fluorescent display from being fluctuated, and the inclination of luminous intensity from being generated by connecting an independent oscillation circuit and a field-effect transistor for driving a filament driving transformer, to each other with a capacitor. CONSTITUTION:The output pulse Q of positive phase for output generated from an oscillation circuit 1 is fed to the gate of an FET 4a via a capacitor 3a. In the meantime, the output pulse Q of negative phase is fed to the gate of an FET 4b via a capacitor 3b. To the gates of the FETs 4a, 4b, diodes 5a, 5b for a level shift with one earthed end are connected, and gate potential is turned negative not to be destroyed. The drain of the FETs 4a, 4b is connected to the start point 6a and terminal point 6b of the primary winding of a transformer 6. The mid-point 6c of the primary winding of the transformer 6 is connected to a power source 7 with the one earthed end. In the meantime, the start point 6d and terminal point 6e of a secondary winding are connected to the filament circuit of a fluorescent display pipe as not shown in a figure. |
