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Our research group has developed an ultra slim and bendable backlight system, which was manufactured by a continuous roll-to-roll process, with a unified component for liquid crystal display (LCD). This backlight system, which has a thickness of 0.26 mm, is simply composed of a light guide film and an optically patterned film made of photocurable resin with micro particles, consequently it does not require any additional optical films such as prism sheets or diffuser. In addition, we have developed a new light guide component which is composed of bundled optical fibers in order to collimate light from the light source to the light guide film. We found that the backlight system could be radiated uniformly across the LCD surface whether plane or curved, and we were able to realize an advanced LCD with good flexibility, high efficiency and high productivity.

A novel edge-light backlight unit using an optically patterned film (OPF backlight unit) for liquid crystal displays (LCDs) is composed of a light guide plate bonded to the top of fine lenses formed on the OPF, a diffusive sheet, a reflective sheet and a light source. A viewing-angle-dependent luminance distribution of the OPF backlight unit was controllable by changing the shape of a fine lens used for the extraction of light propagating through a light guide plate and the direction control of radiating light, and a luminance distribution in a radiation plane suitable for LCDs was realized by adjusting the interval between lenses. Moreover, the extraction efficiency of the OPF backlight unit was greater than that of a conventional backlight unit. Thus, the OPF backlight unit was shown to be promising for the realization of a brighter, lower power consumption, slimmer and lighter LCD than conventional LCDs.

In an edge-light backlight unit using an optically patterned film (OPF backlight unit) with plural light-emitting diodes (LEDs) placed on the side as a light source, dark areas are easily generated between LEDs, because the OPF backlight unit mainly uses the total reflection induced by optical patterns formed on the OPF. Such dark areas were eliminated by narrowing the interval between optical patterns between LEDs and widening it near LEDs. By adjusting the interval between optical patterns across the entire area additionally, a luminance distribution in a radiation plane suitable for liquid crystal displays (LCDs) was realized. Moreover, viewing-angle-dependent luminance distribution can be narrowed by adjusting the shape of the lens-shaped optical pattern. Thus, the OPF backlight unit using plural LEDs was shown to be suitable for small-area LCDs.

We have developed a new precise fabrication technology of a lenticular lens sheet with black stripe patterns for a rear-projection television. The black stripe patterns have to be accurately aligned to cylindrical lenses on the lenticular lens sheet and be able to absorb ambient light. Our proposed technology utilized a photo-sensitive material with a surface modifier which controls surface free energy for surface modification. Using this material, we could obtain two patterned areas which had different surface free energies. Furthermore, fabrication of black stripe patterns on the lenticular lens sheet was carried out by a self-alignment method. This lenticular lens sheet with black stripe patterns had similar optical properties compared with a conventional one.

We have developed light-diffusive UV-curable resins with well-controlled scattering properties by adjusting the diameter of the micro particles and the differential refractive index between UV-curable resin matrix and the micro particles. We expect that optical-patterned films for a slim backlight system can be obtained using them by a roll-to-roll continuous process.

We have developed an ultra slim backlight system using optical-patterned film (OPF backlight), which has a lot of advantages to be composed of a single component and less than 0.4 mm in total thickness. Moreover, we have obtained the possibility to manufacture the sheet of OPF backlights by roll-to-roll continuous process.

The spurious signals appearing in the picture image from a charge-coupled semiconductor device (CCD) camera were removed by means of a novel grating optical low-pass filter (GOLF). By placing the GOLF near the imaging plane of the CCD and adjusting the effective grating period projected onto the imaging plane with respect to the array period, or its integral multiplicative inverse of the picture elements formed in the imaging plane, it was verified that the GOLF eliminated the grating image superimposed on the picture image, which had been a long-standing problem. Photochemical reaction was useful for forming a sinusoidal grating crosssection which increased the MTF value in the region of low spatial frequencies to realize a clear-cut picture image. The GOLF fabricated in the form of a thin plate was promising to realize a new CCD with a built-in optical low-pass filter applicable for downsizing of camera optics.

A grating-type soft-focus filter was fabricated from a polymer film to transform the discontinuous picture of a liquid crystal display (LCD) into a continuous one. The soft-focus filter having a two-dimensional grating pattern with a sinusoidal cross section was photochemically formed on the film by proximity exposure through a photomask to ultraviolet light. When the LCD surface was covered with the soft-focus filter, the output light beam from the LCD was transformed into mainly nine beams as a result of (0, 0)- to (±1, ±1)-order diffractions with nearly equivalent intensities. Thereby, the picture discontinuity caused by the black matrix of the LCD was removed at a small expense of picture contrast.