Application of electromagnetic focusing electron gun in YAG projection CRT

Abstract

An electromagnetic focusing electron gun was used in high-luminance and high-definition YAG (yttrium aluminum garnet) projection CRT successfully. The dual-focusing system in it was developed, which was composed of electrostatic pre-focusing lens and electromagnetic focusing lens. Result from the special optimization of structure and voltage, the electron gun has excellent characteristics especially with high current. As a result, on the green YAG phosphor screen, beam spot diameters of 0.065-0.080 mm at cathode currents of 0.5-1.0 mA. So the horizontal resolution was more than 1200 TV-lines on the 3-in projection CRT screen. Meanwhile, the luminance of 1.4/spl times/10/sup 5/ cd/m/sup 2/ at cathode current of 1.0 mA and anode voltage of 29 kv was achieved.