US 2009/0289558 A1 · DRIVE CIRCUIT OF FLUORESCENT DISPLAY

Abstract

A drive circuit for a fluorescent display that can prevent generation of reactive power in a Zener diode used to generate a cutoff bias voltage. In one embodiment, the drive circuit operates as a single ended primary inductor converter (SEPIC) circuit and includes an input side closed circuit, an output side closed circuit, and a coupling capacitor connecting the two closed circuits. The input side closed circuit includes an input power source, a first inductor and a switching element. The output side closed circuit includes a second inductor, a diode and a second capacitor. A filament of the fluorescent display is connected to the second capacitor. One end of a Zener diode is connected to a negative potential side of the filament and the other end of the Zener diode is connected to an input power source.

Claims6

Dependent claims

A drive circuit for a fluorescent display having a filament, a grid, an anode, and a Zener diode for generating a cutoff bias voltage applied to the grid and the anode, the drive circuit comprising:

an input side closed circuit including first input power source, a first inductor, and a switching element;
an output side closed circuit including a second inductor, a diode and a capacitor;
and
a coupling capacitor;
wherein the Zener diode of the fluorescent display is connected between second input power source and a ground, a negative electric potential side of the filament is connected at a point between a cathode of the Zener diode and the second input power source, and an output voltage of the drive circuit is applied only to the filament.

2 more elements

Dependencies are inferred from the claim text.

Drive circuit of fluorescent display

Life of this patent

Drive circuit of fluorescent display

Life of this patent

Abstract

Claims6