Fluorescent lamp having the cathode and anode with particular angular arrangement

摘要

A fluorescent lamp includes a bulb, a fluorescent material coated on an internal surface of the bulb, a stem, a discharge chamber filled with gas and mercury, a thermal cathode filament coated with electron emitting material, an anode, a pair of lead wires passing air-tightly through the stem and supporting the thermal cathode filament, and a lead wire supporting the anode. The anode is a substantially rectangular plate, and is substantially parallel to the thermal cathode filament in a cross sectional view taken along a bulb axis Z. The thermal cathode filament and the rectangular anode plate can be configured of an angle range of 30-60 degrees in a cross sectional view perpendicular to the lamp axis Z. The rectangular anode plate and the lead wire supporting the anode can be attached to each other in a substantially flag-shaped configuration. The invention produces a smaller discharge spot to improve thermal electron emission efficiency such that efficiency of the fluorescent lamp is improved. Furthermore, over-all size reduction of a fluorescent lamp is possible.