A 6.9‐in. high‐resolution projection CRT for an HDTV display

Abstract

Abstract— The focusing characteristics of a 6.9‐in. projection CRT with a combined electromagnetic and electrostatic focusing system were improved for an HDTV‐display application. To improve the focusing characteristics, a new densely packed phosphor screen with reduced spot growth due to light scattering within the phosphor screen was developed, together with an optimally designed unipotential focusing (UPF) electron gun. Furthermore, a new green phosphor was used to improve the luminance. As a result, beam spot diameters of 0.15 and 0.35 mm were achieved at cathode currents of 0.5 and 5 mA, respectively, with a luminance of 1.3 × 105 cd/m2 at a cathode current of 5.0 mA. An experimental 46‐in. TV set using this projection CRT achieved 900‐TV‐lines horizontal resolution and 1500‐cd/m2 peak luminance. In summary, this projection CRT improves the state of the art of HDTV displays.