Daniel den Engelsen

Color-gamut expansion in CRTs

This paper describes the architecture for a color picture tube (CPT), which enables a cost-effective expansion of the color gamut. Besides a gamut expansion based on application of more-saturated phosphors in the present three-primary system, four- and five-primary systems are described. Gun-pitch modulation allows the application of a conventional electron gun for both a four- and five-primary CRT. In these systems, the mask and matrix transmissions need to be reduced to maintain color purity. From this point of view, a five-primary CRT is unrealistic. Two four-primary CRTs are evaluated in more detail. But, here, the total anode current to generate white has to be increased substantially because of the reduced mask and matrix transmissions. Nonetheless, in this paper it is argued that with one of the four-primary CRTs more-saturated yellow colors can be displayed at 85% of the display luminance of a conventional system without loss of perceived sharpness.

Numerical study of the electron and ion trajectories in HOPFEDs

A hopping-electron field-emission display (HOPFED) is a field-emission display (FED) with a new and revolutionary spacer structure. In a HOPFED, two insulator plates, referred to as hop and flu spacers, are sandwiched between the emitter and front plate. The objective of this spacer structure is to improve the performance of a FED substantially, notably contrast, color purity, and luminance uniformity. Another advantage is the reduced sensitivity of ion bombardment on the field emitters. We show by numerical methods that both the luminance uniformity and the sensitivity of ion bombardment improve substantially in a HOPFED.

The oxide cathode revisited

A new theory is presented on the emission degradation or slump of oxide cathodes at current drawing and on the beneficial effect of doping the emitting layer with rare-earth oxides. It was shown that during its lifetime, a gradual voltage difference is built up in the oxide layer, which eventually leads to the decomposition of BaO and O 2 during current drawi ng. This causes an emission slump in life-tested cathodes. Doping with rare-earth oxides prevents this build up due to the electron donating capability of these materials.

54.1: Invited Paper: Manufacturing of CRTs

The CRT has been the most successful display of the 20th century and it still is at the beginning of the 21st century. The manufacturing of a CRT, consisting of assembling and processing operations, has been completely mechanized. Furthermore, the gradual introduction of more robust processes, which improves quality and yield, and process control via Computer Aided Manufacturing contribute to a significant cost reduction. The recent trend of real flat tubes poses new challenges to the manufacturing of CRTs. The paper focuses largely on tube processing and cost consequences of the real flat trend.