Browsing by Author "Zhang, Yuning"

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A field-sequential-color display with a local-primary-desaturation backlight scheme
(2011-03-01)
Zhang, Yuning
;
Lin, Fang-Cheng
;
Langendijk, Erno H. A.
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光電工程學系
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顯示科技研究所
Field-sequential-color technology eliminates the need for color filters in liquid-crystal displays (LCDs) and results in significant power savings and higher resolution. But the LCD suffers from color breakup, which degrades image quality and limits practical applications. By controlling the backlight temporally and spatially, a so-called local-primary-desaturation (LPD) backlight scheme was developed and implemented in a 180-Hz optically compensated bend (OCB) mode LCD equipped with a backlight consisting of a matrix of light-emitting diodes (LEDs). It restores image quality by suppressing color breakup and saves power because it has no color filter and uses local dimming. A perceptual experiment was implemented for verification, and the results showed that a field-sequential-color display with a local-primary-desaturation backlight reduced the color breakup from very annoying to not annoying and even invisible.
A Hybrid Spatial-Temporal Color Display With Local-Primary-Desaturation Backlight Scheme
(2011-12-01)
Zhang, Yuning
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Langendijk, Erno H. A.
;
Hammer, Martin
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Lin, Fang-Cheng
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光電工程學系
Field-sequential-color mode has benefits on energy efficiency, because colors are made by flashing the backlight red, green, and blue and the color filters are not needed, leading to increased light transmission. However, field-sequential-color mode causes annoying color breakup. In previous studies, a spatio-temporal display has been proposed as a hybrid solution to balance the increase of light transmission and the suppression of color breakup. However, color breakup remains visible for critical image content. In this paper, a 120-Hz liquid crystal display with two-color filters mounted with a backlight consisting of a light emitting diode matrix is introduced. The backlight colors are locally desatured according to the local image content, so the color difference between fields is reduced, and the perceived color breakup is effectively suppressed. Various examples with different color filter and backlight settings are described and analyzed, aiming at different display-performance objectives.
Application of Field Emission as Backlight Unit for Liquid Crystal Displays
(2012-08-01)
Zhang, Yuning
;
Langendijk, Erno H. A.
;
Di, Yunsong
;
Lin, Fang-Cheng
;
光電工程學系
The paper first analyzes the effect of backlight unit for liquid crystal displays on the respect of image quality and power consumption. A spatially and temporally addressable backlight is required in the future liquid crystal displays which have lower power consumption and higher image quality. Compared to the currently used light emitting diode backlight, the simulation results indicate that a rectangular-shaped backlight has better performances on the respect of reducing power consumption and improving image quality. A backlight cell based on the field emission is manufactured and studied. It uses a mixture of multi-wall carbon nanotubes and tetrapod-like zinc oxide nanostructures as the cathode and applies spin-coating process for fabrication. The experiment shows that such field emission backlight unit has a low turn-on field which enables a high backlight luminance at acceptable driving voltage. Besides, this mixture cathode helps to improve the uniformity of field emission in both spatial and temporal domain which is important for the application of backlight unit.