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Pioneer Electric Company has developed a new generation 40-inch rear projection SD-P40 television, a revolutionary, new television that realizes white peak brightness of 300 ft-I and high contrast. The combination of high brightness and high contrast is made possible primarily by newly developed optical-coupling technology that utilizes newly developed concepts. This new optical coupling technology cools the CRT quite efficiently, making it possible to greatly increase the CRT power input to obtain high brightness and at the same time provides greater reliability than direct view televisions. The new optical-coupling technology also makes it possible to almost completely eliminate the reflectance at the boundaries between the CRT and the lens and air, which gives much higher contrast than previous televisions. Not only does this optical-coupling technology provide high performance, in addition since the liquid coolant it employs functions as a liquid lens, the coupling lens can be designed to a uniform thinness and a small aperture. This greatly reduces the cost of the lens. Our newly developed optical-coupling technology is the ultimate form of cooling for the CRT tubes of projection televisions and coupling with the lens and will become the mainstream technology in the future. It is forecast that other manufacturers will also adopt this type of technology. The optical lens section, which is the heart of a projection television, is a hybrid structure with three aspherical plastic lenses and one glass spherical lens. It has higher performance image formation and greater temperature stability than previous televisions. The plastic lenses are all finished with multi-coating to hold down light loss and maximize transparency. This con-tributes greatly to increasing the brightness for a projection television. Previous 3-tube type projection televisions were bothered by low color uniformity, color shift, and low color rela-tive illumination. This model uses three bends in the optical path to lengthen the optical path and reduce the R, G, and B lens pitch angle, so these problems can be virtually ignored. In particular, the special design of the lenticular lens screen greatly. suppresses color shift. The rear surface of the screen is printed with black stripes to hold down. reflectance from outside light sources and minimize the reduction of contrast in bright rooms. In addition, the opti-mal design of the fresnel lens keeps the hot band from being too noticeable. A variety of steps were taken in the design of the bends in the optical path to prevent ghosts.
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