Screening of color phosphor powders on CRT faceplates

Abstract

Abstract— We studied the screening of color phosphor powders on CRT faceplates by photolithography. For photolithography, the phosphor particles should disperse perfectly in the dried PVA‐phosphor screens. The desired pattern sizes and adhesion of the patterned phosphor screens can be calculated with these dried PVA‐phosphor screens. To achieve dry screens with smooth and uniform layers of phosphor particles, phosphor powders should be made with round particles, with the sizes distributed in a narrow range. The phosphor particles perfectly disperse in PVA‐phosphor slurry without the addition of surfactant if an aging process is used. Adding surfactants to the PVA‐phosphor slurry results in the aggregation of phosphor particles in the dried PVA‐phosphor screens, contrary to expectations. Color phosphor screens with a triad pitch of 72 μm have been made with the aged PVA‐phosphor slurry.

Cathodoluminescent phosphors

“…If the electron beam with diameter f e is incident on the phosphor screen, the diameter f em of the emitted area is usually wider than f e . According to a geometrical analysis of f em , 113,115 the widening is limited to one particle size f. Hence, f em is given as…”

Cathode Ray Tube Phosphors

“…Since an ideal phosphor screen is made with n = 2, the minimum pattern size of an adhered phosphor screen is given as Figure shows the pattern sizes of an ideal phosphor screen as a function of the exposure doses of UV light. The ADC concentration for phosphor screens with n = 2 is 4 wt % in 100 g of PVA resin 39 Pattern sizes of defect-free phosphor screens as a function of the exposure doses of UV light. …”

“…This is due to the aggregation of phosphor particles in the PVA screens. The screens have many pinholes . The constant pattern sizes result from the photolithography in the localized pinhole areas in the patterned screens with high ADC concentrations.…”

“…With poor reproducibility, a number of in-house trade secretes have been developed by screening engineers. This kind of approach is an impediment to scientific studies on the screening of phosphor powders, resulting in only a few scientific publications. − …”

“…The ADC concentration for phosphor screens with n ) 2 is 4 wt % in 100 g of PVA resin. 99 When the phosphor screens are produced using commercial phosphor powders under the established screening procedures (specifications), one obtains the curve shown in Figure 40, instead of that in Figure 39. This curve has a constant width of the patterned screen in the high-dose range.…”