Cheng Jian-bo

High luminance YAG single crystal phosphor screen

Abstract Epitaxial phosphors of Ce,Tb:YAG containing Lu3+ and Ga3+ on YAG (yttrium aluminum garnet) single crystal faceplates have properties which are suitable for projection CRTs. The external efficiency of the single-crystal YAG screen is relatively low. Truncated cone geometry can increase the external efficiency by a factor of 5.2, if such a shape can be formed in the phosphor layer. An anisotropy etching process of YAG has been developed for the fabrication of a YAG luminescent screen with truncated square mesas. A large fraction of the cathodoluminescent can be directed through the untextured front surface of the crystal. An improvement in phosphor efficiency by a factor of 2.3 has been achieved.

Application of electromagnetic focusing electron gun in YAG projection CRT

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.

Brightness measurements of electron beam photoemitted multicrystalline I/sub a/B/sub 6/

Lanthanum hexaboride has been tested as a photoemitter when irradiated by a KrF eximer laser. Measured current, from 0.4cm/sup 2/ emitting area, was 10 A at irradiating wavelength of 248 nm; current density was about 25 A/cm/sup 2/. Beam normalized rms emittance measured with pepper pot method was 20 mm-mrad. The corresponding normalized rms brightness was about 2.5 X 10/sup 10/ A/cm/sup 2/-rad/sup 2/. The quantum efficiency was about 1.0 X 10/sup -4/ . The chamber pressure radius was better than 2 X 10/sup -6/ torr. Further research is underway.