The objective of this research was to develop a high efficiency backlight for liquid crystal displays (LCDs). A typical LCD panel includes a pair of dye polarizers. The polarizer functions by ...absorbing light of one component and by allowing the other component, which has a plane orthogonal to the first component, to pass through the polarizer. Therefore, the polarizer absorbs at least 50% of the light illuminated onto the LCD panel if it is unpolarized. Hence, the ratio of the light from the backlight absorbed by the polarizer need to be reduced to achieve low power consumption in the LCD. Light output at the interface of refraction is known to contain more p-polarized light than s-polarized light, and this can be attributed to the transmittance difference between the two kind of light there. We make use of interface refractions from existing optical components and maintain the state of polarization as light passes through them. In accordance with this concept, we have successfully developed a polarized backlight utilizing a p-polarized light out-coupling by effectively using the interface refractions of optical components. In our backlight, the luminance for the p-polarized light was improved by 30% or more compared to that of a conventional backlight. In addition, this backlight can be composed of fewer components. Therefore, low power consumption can be achieved by applying our backlight to LCDs, and the added benefits are that the module can be made thinner and at low cost.
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