Optical cross talk in LED displays with light scattering optical cavities.

The influence of optical cross talk between segments in LED displays with scattering optical cavities on contrast is discussed. Numerical values of contrast are calculated for various displays with and without ambient illumination and methods of contrast improvement are considered.

Light extraction efficiency from LED displays with scattering optical cavities.

A model enabling determination of light extraction efficiency from stretched segment LED displays with scattering optical cavities is given. Calculations were performed for various cavities, and numerical results are compared with measurement results reported in available literature.

Light extraction efficiency of LED displays with perpendicular parallelepiped transparent optical cavities.

In this paper formulas are derived describing the light extraction efficiency of the transparent perpendicular parallelepiped optical cavities in LED displays. The efficiency is calculated for a mirror-wall cavity and for a cavity having walls formed by an air-epoxy interface. Results show that optical efficiencies of these cavities are almost identical and equal to approximately 13%.

Optical efficiency of LEDs with hemispherical lenses.

In this paper formulas are derived that describe the optical efficiency of an LED package consisting of a hemispherical lens placed on the cylinder. The dependence of this efficiency on the H/R ratio and the epoxy coefficient of refraction is calculated. In calculations it is assumed that the semiconductor chip, believed to be the point source of radiation, is mounted on the optical axis of the LED package, and the absorption of nonscattering epoxy is small.

Optical efficiency of LED displays with cylindrical transparent optical cavities.

Formulas are derived describing the efficiency of light extraction from LED displays with transparent optical cavities. The efficiency is calculated for mirror-wall cavities and for cavities having walls formed by the air-epoxy interface. Results show that typical efficiency values for such cavities are 15% and for suitably designed air-filled cavities ~29%.