18.1: Adaptive Dimming Technique with Optically Isolated Lamp Groups

Abstract

An adaptive dimming technique is examined for an LCTV in which horizontally aligned eight parallel backlight lamps are provided. The lamps are optically isolated one another and can be dimmed independently depending on the TV signal. The optical isolations are found to be especially effective to relatively dark pictures having few bright spots. The backlight power for the sample pictures with APL ranging from 0.8% to 40% can be reduced to 20% -65% by adopting the dimming technique.

26.4: Algorithm for Contrast Reserve, Backlight Dimming, and Backlight Boosting on LCD

“…Thus our method allows a more aggressive dynamic backlight dimming strategy than usual, without resorting to 1D or 2D spatial backlight dimming (a.k.a. "highlighting backlight") [1]. But be aware that even a single bright object of sufficient size in the entire image will turn the backlight on.…”

44.4: RGB-LED Backlights for LCD-TVs with 0D, 1D, and 2D Adaptive Dimming

“…A principle of the adaptive dimming technique is explained in refs. [1] and [3]. The technique dims luminance of the LED in block (m, n) from the initial value L b (m, n) to L a (m, n) by a factor k(m, n) (<1), namely, L a (m, n) = k(m, n)·L b (m, n).…”

“…For reducing the power consumption, backlight luminance is reduced by a dimming factor k, and, at the same time, video signal is enhanced by a factor 1/k, according to the input video signal. Since the LED backlights can adopt a structure in which the backlight unit is segmented into small regions, unlike CCFLs, the power reduction is more pronounced compared with CCFL backlights [3]. The adaptive dimming technique also allows compensation of backlight luminance non-uniformity, enhancement of gray scale capability for low luminance images, and improvement of dark room contrast [4,5].…”

Design method for a thin uniform direct backlight using a diffuser plate with a pattern on the surface and optical films

“…However, the edge-lit LED backlight is somewhat higher priced than the direct backlight because it is composed with a LGP made of high grade acrylic and a heat sink for LEDs. The direct backlight has an advantage in local dimming technologies [2,3,[9][10][11], which improve picture quality and low power consumption. Therefore, a thin direct backlight is required.…”