THE ZNGA2O4 PHOSPHOR FOR LOW-VOLTAGE BLUE CATHODOLUMINESCENCE

The ZnGa2O4 phosphor has been investigated for its application to vacuum fluorescent displays (VFDs) utilizing low-voltage cathodoluminescence. It is expected that this oxide phosphor does not cause damage to filaments in VFD's, while it is a serious problem for conventional sulfide phosphors. This phosphor shows blue luminescence with a spectral peak at 470 nm and a chromaticity at X = 0.170 and Y = 0.130. A luminous efficiency of 0.7 lm/W has been obtained, when the VFD with this phosphor is operated at 30 V dc. The results of high-temperature operating life test have proven the excellent stability of VFDs utilizing this phosphor.