Evaluation of the thermal design of a liquid-lens cooling system for projection picture tubes

The thermal design of a liquid-lens system for cooling picture tubes in projection television receivers is evaluated using an experimentally benchmarked numerical model. Because of the intense brightness in the visual image, excessive waste heat is generated as the by-product of light emission fi‘om the phosphor screen as the electron beam sweeps across the raster region at the back of the face panel. Projection tube specifications indicate a maximum allowable temperature at the face-panel center and a maximum allowable temperature differential between the center and perimeter points. To cool the tube’s face, an optical liquid (liquid lens) fills the space between the face panel and a meniscus lens directly in front of it. A metallic enclosure frame serves as support for the meniscus lens and a container for the liquid. Heat is transferred by natural convection from the face panel to the enclosure frame and from there to the interior environment of the television cabinet by convection and radiation.