Output luminance of an RGB‐LED backlight for an LCD‐TV was adaptively dimmed along with input video signal in fashions of 0D (uniform dimming), 1D (line dimming), and 2D (local dimming). It has been proven experimentally that the backlight power can be reduced to 83%, 71%, and 50%, respectively, for a typical sample movie having 8.0% post‐gamma average picture level (which is equal to the average luminance level). Further simulation study revealed that the power consumption can be reduced to the value equal to that of the post‐gamma APL.
We demonstrate large-area, closely-packed optical vortex arrays using self-assembled defects in smectic liquid crystals. Self-assembled smectic liquid crystals in a three-dimensional torus structure are called focal conic domains. Each FCD, having a micro-scale feature size, produces an optical vortex with consistent topological charge of 2. The spiral profile in the interferometry confirms the formation of an optical vortex, which is predicted by Jones matrix calculations.
Bending a planar organic light‐emitting diode (OLED) alters the optical structure of the device, resulting in the change of optical characteristics. The bending effect on light emission through the substrate was analyzed, and the issues were extracted. The effect of curvature radius on characteristics of nonplanar OLED light sources was experimentally studied. For this purpose, two OLED samples with barrier layer thicknesses of 100 and 150 nm were fabricated, and their characteristics were measured at curvature radii of R0 = ∞ mm (flat state), R2 = 143 mm (cylindrically curved state), and R5 = 56.7 mm (cylindrically curved state). The variations in optical characteristics such as total luminous flux, the luminous intensity pattern, and the spectrum were verified by measuring the cylindrically shaped OLEDs. The results were evaluated and discussed for OLEDs in cylindrically curved states.
A directional backlight unit has been developed for widening the viewing angle of a TN-LCD with a front-surface-light scattering film. The novel directional backlight has a diagonal of 34-cm and is structured by light-direction control micro features and an inverted prism film. The backlight has a round luminance cone of +/-9 deg. and a uniform spatial distribution of 90%. In combination with the LCD, the narrow cone resulted in widening of the TN-LCD's viewing angle up to 120 deg. FWHM.
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