Luis Manuel Murillo-Mora

Novel diffraction grating light guide for LED backlight

In conventional LED backlight as that used in mobile liquid crystal displays (LCDs), typically the structure consists of a light guide, a diffusing sheet, prism sheets and so on. In this work we would like to propose a novel light guide where we have applied a special diffraction grating technology which provides a high performance with a thinner backlight. The special designed diffraction gratings on the light guide redirects incident light by diffraction to the front direction without the utilization of prism sheets. For testing the performance we made a diffraction grating light guide suited for a 2.4 inch backlight with 4 LEDs in a trial. As a result, the backlight that consisted of a diffraction grating light guide, with either a single or none prism sheet achieved equivalent performance to conventional backlights.

A new type of optical diffuser with the directional property

A diffusive film characterized with a directional property was developed. This new type of diffusive film is achieved with a new technology derived from holography. Directionality of diffusive film is characterized because it diffuses the light from the determinate angle strongly more than other angles. This discriminative property is consequence of the diffusive film structure that consists of different index transparent materials. Additionally, The film is a volume type diffuser, and the surfaces are almost flat so it is possible to laminated it to various part of other elements without remarkable affecting the diffusing properties of the film. Moreover, durability of this film is actually enough to consumer applications. With these remarkable properties, this diffusive film can widely applied to display systems etc.

Holographic reflector for reflective LCDs

We describe a new holographic optical element to improve the images quality of a reflective liquid crystal displays (LCDs). This new holographic reflector consists basically of 2 layers: a volume type transmission hologram layer and a metallic reflection layer. Compared with conventional reflectors for reflective LCDs, a high optical efficiency can be obtained because the hologram is able to concentrate the reflected light to the observers eyes. Also, it avoids the problems of glare in the LCDs by deviating the reflected incident light (used for display) away from the direction of the direct reflection light. The transmission holograms low wavelength selectivity permits us to obtain a near white color reflector for reflective LCDs which for multiple applications is the preferable color for the background.

Hologram technology in the display field

A review of the applications of holography to commercial products is presented. This review is performed on application on display devices such as liquid crystal display devices where the inclusion of holographic optical elements has been successful. Works are focused on light coupling, reflectors, diffusers and light guides.

Transmission type holographic reflectors

Holographic reflectors have proved to be a viable solution to help to increase the luminance of current reflection mode LCD displays at a low cost. Here we present some alternative holographic reflectors being considered at Toppan Printing Co. Inc. for liquid crystal display applications. The reflectors show a peak brightness near the perpendicular viewing direction and are able to provide a white appearance in a wide viewing are a or a sharp color dazzling appearance.