Fujifilm Working to Make LCD Screens Brighter With Better Color, Filing Shows

A team of five Fujifilm engineers in Tokyo has been in “intensive studies” for years on ways to make LCD TV screens brighter and with better color reproduction, while using less power. The work centers on Panasonic TV sets that the team “disassembled” and then rebuilt with modified backlights and additional light-reflecting and light-processing film sheets. The work is described is a series of Fujifilm patent applications filed between December 2013 and June 2016, and summarized in a document published Dec. 1 at the U.S. Patent and Trademark Office as US 2016/0349573. The published application runs 74 pages of dense text and technical drawings, complete with chemical and optical detail, and describes many practical experiments the Fujifilm engineering team undertook for several years. But the basic idea for enhancing “front brightness” and “color reproduction range” can be summed up quite simply. A modified backlight is used that emits blue light with wavelengths ranging between 380 and 480 nanometers, the document says. The light is projected onto an optical conversion sheet with quantum dot fluorescent particles, which converts the blue into component light with longer wavelengths, such as green (around 535 nanometers) and red light (around 630), it says. The effect is enhanced by a sandwich of several liquid crystal polarizing sheets that variously reflect and concentrate light in broad bands of 470-510 nanometers (blue-green), 560-610 nanometers (yellow-orange) and 660-780 nanometers (reddish), it says. One of the Panasonic TVs that Fujifilm used for the experiments was a commercially available LCD model TH-L42D2, its factory backlight replaced with an RGB narrow-band backlight that included a 465-nanometer-wavelength blue LED from Nichia, it says. The quantum-dot optical conversion sheet was laminated with the reflective sheets and placed in the front portion of the light source, it says. For some experiments, a reflective sheet also was placed at the rear of the light source, it says. The studies found it was possible to boost the front brightness of some of the modified panels by upwards of 27 percent, it says.