High-luminance and high-resolution CRT for projection HDTV display

We have developed a 3-in. YAG (yttrium aluminum garnet) projection CRT for an HDTV display. The densely packed phosphor screen with a multi-layer interference filter is prepared by depositing phosphor on a YAG faceplate using a centrifugal sedimentation method. The tube's envelope is made from a glass whose expansion coefficient is well-matched with that of YAG. The focusing characteristics of an optimally designed pre-focusing electron gun and focusing magnet are improved for a HDTV display application. As a result, the green, red, and blue tubes reached luminances of 1.4×10⁵, 6.2×10⁴, and 8×10³ cd/m² at a cathode current of 1.0 mA and an anode voltage of 29 kV, respectively, with a half-intensity linewidth of 85 μm. An experimental 48-in. rear-projection TV set using the YAG projection tubes achieves more than 1000-TV-lines horizontal resolution and 300-cd/m² mean white luminance.