Luminous Efficiency Improvements of Color Phosphors Used in Vacuum Fluorescent Displays

The luminous efficiency of yellowish green and blue phosphor has been greatly improved. A luminance of 400 cd/m² can be obtained at 12V with the yellowish green phosphor, whose luminance efficiency increased to 130%. This improvement suggests that the yellowish green phosphor can be used in the 12V driven VFD for the automotive application as well as greenish yellow and yellowish orange (1)*, (2)*. With respect to the blue phosphor, the luminance efficiency has been increased up to 160%, thus reducing the input power down to about 63%. By the continuing improvement, the blue phosphor will also be available in the 12V driven VFD.