Title :
Ir-coated dispenser cathode for CRT
Author :
Kimura, Sakae ; Yakabe, Toru ; Matsumoto, Sadao ; Miyazaki, Daisuke ; Yoshi, Tsuyoshi ; Fujiwara, Minoru ; Koshigoe, Shimpei
Author_Institution :
Toshiba Corp., Kawasaki, Japan
fDate :
12/1/1990 12:00:00 AM
Abstract :
A compact dispenser cathode has been developed for application to cathode ray tubes (CRTs). A cathode emitter, comprising BaO, CaO, and Al 2O3 in a molar ratio of 4:1:1, was impregnated into a porous tungsten pellet. An intermetallic compound of tungsten and iridium was formed on the cathode pellet. Heater ratings were 6.3 V×0.2 A. Emission characteristics were measured by using color CRTs. As a result, a cathode peak loading of 15 A/cm2 was ensured in the space-charge region. Furthermore, life tests with a peak loading of 7.5 A/cm2 were conducted over 10000 h. The decrease in emission current after 10000 h was within only 10% of the initial value. Reliability of cathode performance was assured in terms of breakdown potential between the heater and the cathode, emission characteristics, life performance, grid emission, and the drift in cutoff potential. In addition, the effects of the coating thickness on the emission characteristics are discussed
Keywords :
cathode-ray tubes; cathodes; iridium; life testing; BaO-CaO-Al2O3; Ir coating; W-Ir; breakdown potential; cathode emitter; cathode peak loading; cathode ray tubes; coating thickness; color CRTs; cutoff potential drift; dispenser cathode; emission characteristics; emission current; grid emission; heater ratings; life performance; life tests; porous W pellet; reliability; space-charge region; Aluminum oxide; Cathode ray tubes; Coatings; Electric breakdown; Fabrication; Intermetallic; Life testing; Temperature; Tungsten; Welding;
Journal_Title :
Electron Devices, IEEE Transactions on
