PERFORMANCE OF ZEUS DISPLAYS

It is shown that the overall performance of Zeus displays is quite goo d, as illustrated by photographs of operating panels displaying 'CRT-q uality' TV pictures. Results of measurements of all relevant performan ce parameters are presented, as well as an analysis of these data in r elation to the design and operation of the displays. Measurements of t he luminance as a function of the screen current density and of the sc reen voltage of Zeus displays are reported. A white D-65 luminance of 1000 Cd/m(2) is obtained at a screen voltage of 4.5 kV and a screen cu rrent density of about 9 mu A/cm(2). The luminous efficacy of the phos phor screen in the panels is found to be 12 lm/W (in the absence of sa turation) for white D-65. The efficacy of a 17 '' Zeus panel (includin g transport power dissipation, cathode heating power and addressing po wer) is about 4 lm/W. The factors determining the internal contrast an d colour purity of Zeus panels are discussed. Experiments to determine the relevant contrast parameters are described as well as the results of direct measurements of the internal contrast, colour purity and co lour selectivity. Internal contrast values of more than 1000 have been obtained, and a colour selectivity better than 700. The available col our gamut is close to that of CRTs. Preliminary measurements of the ex ternal contrast of 17 '' panels with a black matrix and front glass wi th 50% optical transmission yield a contrast value of 60 at an ambient light level of 100 lux. The factors determining the picture uniformit y in Zeus displays are discussed. Several panels with good uniformity have been realized. No artefacts associated with moving pictures occur , the only significant artefact is caused by charge transfer effects. The visibility of this effect can be sufficiently reduced by using sui table 'flush' pulses and by optimizing the geometry. The displays used for the performance measurements have a quincunx dot arrangement and dot pitches 0.5 x 0.6 mm, giving PAL resolution on 28 '' panels. Small experimental panels with pitches of 0.3 x 0.5 mm and 0.25 x 0.30 mm h ave been realized and operate satisfactorily. The viewing angle of Zeu s displays is close to 180 degrees. Preliminary tests show that lifeti mes well over 10,000 h are possible if the glass surfaces hit by elect rons are covered with an MgO coating and if the blue phosphor is coate d with a very thin calcium polyphosphate layer.