Luminoz Inc., a manufacturer of projection screens, etc., developed a screen that can reduce the depth of a rear projection TV to about 12 cm.
Targeting the commercialization in 2008, the company is presently promoting the development in collaboration with leading electronics manufacturers in and outside Japan.
The new screen can eliminate the need of a large mirror that is necessary in the existing rear projection TVs. Moreover, according to Luminoz, the existing screen that is composed of two sheets respectively provided with lenticular and Fresnel lenses can be replaced with a single sheet.
The sheet has a single-piece structure that integrates three layers: the layer called the "curve lens," the "black block layer" and the diffusion layer. The curve lens has functions equivalent to those of mirror and Fresnel lens, the black block layer can serve as black stripes and the diffusion layer can act in place of a lenticular lens.
In a rear projection TV employing this screen, a light projected from just below the screen is totally reflected by the curve lens so that the reflected light is collected on transparent portions of the black block layer. Then, the light goes through the diffusion layer to be displayed on the screen. To reduce the thickness of a rear projection TV, the light source must be placed closer to the screen.
Luminoz made it possible to project the light from directly below the screen by the adoption of the curve lens. Consequently, a large mirror, which is required in the existing rear projection TVs, can be excluded, thereby reducing the thickness of a rear projection TV to as thin as 12 cm.
Increased contrast ratio
Another feature of the new screen is that the light subjected to total reflection on the curve lens is once condensed on the front face of the screen. Thus, by using the transparent portions of the black block layer as the light collection portions, the area of the black portion can be increased in the black block layer, resulting in a higher contrast ratio on the screen.
According to Luminoz, the black contrast ratio, which is about 70% in the existing screens, can be increased to about 90% because the gap between the transparent portions (pitch of black portions) only measures 8 μm. The black block layer is transparent at the time of production, but it is blackened by the irradiation of a special light.
Meanwhile, Luminoz used its proprietary polymer sheet capable of diffusing light in different directions for the diffusion layer. Therefore, the layer is provided with a function equivalent to that of a lenticular lens.
The new sheet is composed of two kinds of polymers with different refractive indices regularly aligned in a vertical direction. In this way, the phases are displaced with respect to each other by birefringence, thereby enhancing the diffusion.
Luminoz is moving to commercialize the new screen for use in 65-inch or larger rear projection TVs. In addition, the company expects that the product is also applicable to backlight units of large size LCD panels.
Luminoz is a venture company established in the United States in 1999. The headquarters is moved to Tokyo in 2002. The current main shareholders of the company include Globis Capital Partners, Works Capital Inc., Mitsui & Co. Ltd., The Dow Chemical Co.