Michitaka Ohsawa

A fully digital convergence system for projection TV

A high-precision fully digital convergence system for home-use PTVs (projection televisions) has been developed. The use of digital circuits and the curved-line interpolation technique can reduce the misconvergence to less than 2 mm (it is 4-6 mm in the conventional system). The use of time-division processing in the digital-to-analog converter and the newly developed gate array realizes a low-cost system and reduces the number of variable resistors to 6 (there are 30-45 in a conventional system). The system can handle nonstandard signals reproduced from VCRs, and can also be applied to EDTV, HDTV, and so on. >

A 46‐in. high‐resolution rear‐projection display

— We have developed a 46-in. high-resolution high-luminance compact rear-projection display that can automatically display in three modes: ID (NTSC), ID-vista (NTSC), and HD. The main specifications of the display are 800 TV lines of horizontal resolution (aspect ratio 16:9), peak luminance of 1370 cd/m2, 100:1 contrast ratio, and depth of 672 mm. We report on the technology required to realize this high performance.

A high-resolution rear projection TV for home-use

The typical characteristics of a newly developed 42-in compact PTV (projection TV) with high picture quality are shown. Descriptions are given of the optical system; the CRT and its accessories, comprising a dual focusing system, a focusing magnet, a six-pole convergence yoke, and a new green phosphor; and the digital convergence system. >

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

The focusing characteristics of a 6.9-in. projection CRT with a combined electromagnetic and electrostatic focusing system were improved for an HDTY-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 × 10 5 cd/m 2 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/m 2 peak luminance. In summary, this projection CRT improves the state of the art of HDTY displays