End-of-life detection of discharge electrodes by taking current-voltage characteristics of a fluorescent lamp

Abstract

Current-voltage characteristics of a fluorescent lamp slowly change in accordance with the degradation of the electrodes. In the operation with a high frequency electronic ballast for a fluorescent lamp, change of electric current running through the electrode causes a sudden decrease in thermionic electron emission from the electrode working as a discharge cathode. This characteristic appears in one direction of current flow as the lamp is operated for a long time corresponding to the loss of oxide coatings from the electrode. Methods to distinguish degradation of electrodes of a fluorescent lamp are discussed.