Erno H. A. Langendijk

A New Color Breakup Measure Based on Color Difference Between Fields and Contrast to the Surrounding

Field-sequential-color displays can have low power consumption and high spatial resolution, but can suffer from annoying color breakup. Various approaches to suppress color breakup have been presented in recent literature. However, a suitable color breakup measure is necessary to compare the performances of those approaches, and is also helpful for quick evaluation of algorithms and parameter settings. A perception experiment was carried out to investigate the perceived color breakup with different field color combinations, different light intensities, and different backgrounds. The results indicate that the color difference and the relative contrast between fields have a significant effect on the perceived color breakup, rather than the absolute luminance value, which is different from existing metrics for color breakup visibility. Based on this new insight, a computational metric for color breakup visibility is proposed and discussed, which has a high correlation with the subjective scores (R2 = 0.945).

A field-sequential-color display with a local-primary-desaturation backlight scheme

— 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

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 LCDs

Liquid crystal displays (LCDs) have become main stream in the flat panel display industry and the use of light emitting diode (LED) array as a backlight unit (BLU) for LCDs is emerging. However, the currently used LED for the backlight unit is a point light source and due to the optomechanical limitations, the LED backlight is not an ideal rectangular backlight. Fortunately, a BLU based on field emission satisfies such demand. The point spread function (PSF) for both LED and field efect back light unit (FE BLE) are shown. The simulation results indicate that the good property of field emission (FE) as a flat light source shows its prospective feature in the application as the BLU for LCDs.

46.3: Ultra Wide–Gamut LCD Using a Local Multi–Spectral Backlight

Conventional LCDs cover about 33% of the visible gamut in CIE1976 (u′, v′)-chromaticity space. This paper describes a display concept covering more than 63%. It consists of an LCD and a backlight with 5 LED types. From the spectra, a model is derived. The model is used to examine the gamut. Computations are compared with measurements from a demonstrator.

65.2: A 120Hz Spatio‐Temporal Color Display Without Color Breakup

A color breakup reduction method is proposed for a 120Hz spatio-temporal color display. It has a 1.5 ×∼3 × high transmission ratio and a 1.5 × high resolution compared to a normal liquid crystal display (LCD) with RGB (red, green, and blue) color filter. It can be implemented on a 120Hz LCD with two-color filter and a local dimming RGB LED (light emitting diode) backlight. It algorithmically suppresses the color breakup by reducing color differences between fields with a local-primary desaturation protocol in a segmented backlight.