A wide-viewing-angle liquid-crystal display using front-scattering film and directional backlight

A combination of front-scattering film and directional backlight has been proposed as a system for wide-viewing-angle transmissive liquid-crystal display (LCD). This system does not require precisely controlled phase difference film presently used in commercial LCDs, which is expected to make LCDs simpler and less expensive. However, this system has not, as far as we know, been put into practical use due to the blurring of images and the whitening of the scattering film that causes the degradation of contrast. In this article, we designed a scattering film that causes little blurring of images and whitening by optimizing conditions of light-scattering particles added to a polymer film and addition of the dye. The blurring of images was inhibited by doping polymer film with particles of high relative refractive index. The whitening of the scattering film was inhibited by the addition of the dye. The film in which particles were dispersed and accumulated showed different luminance properties and blurring of images at the same particle concentration. Finally, a directional backlight covered with the optimized scattering film showed equivalent luminance properties to those of a commercial backlight and demonstrated the feasibility of this system.