Focusing Properties of ThinCRT™ Display

Abstract

Candescent has developed a field emission flat panel display, the ThinCRT, based on high voltage phosphors to take advantage of their high efficiency, long life, commercial availability, and wide color gamut. This paper discusses the unique system developed to focus the electrons across the 1.25 mm anode/cathode gap required for high voltage operation.

Field Emission Flat Panel Displays

“…The larger distance between the FIGURE 7.25. Methods for generating focused electron beams: (a) in-plane, thin film focusing of each emitter [43]; (b) double-gate, thin film focusing of each emitter [43]; and (c) thick film focusing of a group of emitters [26,45].…”

“…At present, the method of choice in the FED industry is that of Fig. 7.25(c), which is more of a beam confinement method rather than true individual tip focusing [26,45]. Modeling results have shown that the best focusing is obtained with the double gate structure, followed by the in-plane structure, and then by the waffle structure [46].…”

“…A microphotograph taken with a digital camera of light emitted from a display using a 40-m thick film focusing "waffle" is shown in Fig. 7.26 [45]. The column pixel pitch is 94 m.…”

Technological Overview

“…However, before they mix, one can build Einzel lenses onto individual clumps of emitters. These are typically small converging lenses built into the gate structure, and they function to reduce the perpendicular momentum of individual emitter sites before the electron beams merge and lose the information of the emitter's identity [51,52]. However, lens structures suitable for beam tubes are still far from practice.…”