Cathodoluminescent characteristics of a spherical Y2O3 : Eu phosphor screen for field emission display application

Abstract

The cathudoluminescent characteristics (CL) of a spherical Y2O3:EU phosphor screen were investigated for field emission display application. The phosphor screen as an anode plate was vacuum sealed (similar to 3 x 10(-6) Ton) with 0.7 in, diagonal Si-based Mo tip field emitter array with 25 X 25 pixels. It was prepared by electrophoretically depositing spherical Y2O3:EU phosphors, which were synthesized by the aerosol pyrolysis method. The character image was displayed on this anode plate by an external driver circuit with PWM driving scheme. The CL brightness of 41 cd/m(2) with CIE chromaticity of x = 0.649, y = 0.346 could be obtained at 400 V anode voltage and 55 V gate voltage inducing a 48 mu A/cm(2) current density in the de mode, corresponding to 0.63 lm/W. However, screen efficiency could be increased to 1.24 lm/W by reducing the charge dose on the screen, of which the operating conditions were of 400 V anode voltage and 60 Vp-p gate voltage inducing an average 30 mu A/cm(2) emission current density in 15% pulse mode. It was found that the electrical resistivity of the phosphor screen was the origin of a pool image of displayed character and even caused a sudden decrease of emission light. The charging effects of spherical Y2O3:Eu phosphors screen on the luminance under low voltage operation are examined in this work and the methodology for enhancing picture quality is discussed based on experimental observation. (C) 2000 The Electrochemical Society. S0013-4551(99)09-013-8. All rights reserved.