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

The cathudoluminescent characteristics (CL) of a spherical Y2O3:EU phosphor screen were investigated for field emission display application. The phosp hor 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 pixe ls. It was prepared by electrophoretically depositing spherical Y2O3:EU pho sphors, which were synthesized by the aerosol pyrolysis method. The charact er image was displayed on this anode plate by an external driver circuit wi th PWM driving scheme. The CL brightness of 41 cd/m(2) with CIE chromaticit y 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, corr esponding 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 c onditions 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 fo und that the electrical resistivity of the phosphor screen was the origin o f 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 experim ental observation. (C) 2000 The Electrochemical Society. S0013-4551(99)09-0 13-8. All rights reserved.