The trinitron tube
The Trinitron uses a single in-line gun assembly and a single electron lens assembly as shown in Figure 9.11. The phosphors are arranged in vertical
stripes forming three-colour striped triads. Higher electron transparency is achieved as fewer electrons are lost by hitting the mask resulting in improved efficiency and brightness. The single electron gun employs three in-line cathodes. The three beams pass through a complicated anode arrangement which bends the two outer (red and blue) beams so that they seem to be emanating from the same source as the green beam in the middle. The Trinitron suffers from two basic disadvantages. The first is that the construction of the striped mask has very little stiffness in the vertical direction and has to be kept under considerable tension to prevent sagging or buckling. The second disadvantage is the need for some dynamic convergence adjustments especially in wide angle large screens.
The PIL tube
In the precision-in-line, PIL tube, three separate guns are mounted side by side on the same horizontal plane. The phosphors are painted in vertical stripes with the shadowmask consisting of staggered slots (Figure 9.12) providing mechanical rigidity and high electron transparency for improved brightness. The main advantage of the PIL tube is the develop- ment of astigmatic magnetic field produced by a special deflection yoke designed to produce staggered magnetic field to eliminate the need for dynamic convergence.