DRIVE CIRCUIT OF FLUORESCENT DISPLAY TUBE AND PLANAR GRID TYPE FLUORESCENT DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To reduce a cutoff voltage to be applied to an anode to irreducible minimum and to improve display quality. ;SOLUTION: A constant voltage diode 34 is grounded through a resistor R1 and the cathode 20 of the diode 34 is connected to a central tap of a transformer 33. The anodes 25A-25C are connected to respective drains of FETs 29A-29C through the resistors RA. A constant voltage diode 35 whose cathode is connected to the anode of the constant voltage diode 34, and a negative source -VDISP is applied to the anode. A source voltage VCC is applied to respective sources of the FETs 29, 31 of an anode drive means 26 and a grid drive means 27. When the prescribed anode 25 is light-emitted, the cutoff voltage lower by Ek₂ than the cathode 20 potential is applied to the anode 25 to which a segment signal is not applied. Further, the cutoff voltage lower by Ek₁ than the cathode 20 potential is applied to a grid 19 to which a figure selection signal is not applied.;COPYRIGHT: (C)1998,JPO