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

Shirai, Tetsuya; Shimizukawa, Sho; Shiga, Tomokazu; Mikoshiba, S.; Käläntar, K.

doi:10.1889/1.2433283

Cited by 65 publications

(54 citation statements)

References 2 publications

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“…Backlight-dimming technology, originally developed to enhance the dynamic contrast ratio, also reduces power consumption [61,77,78]. Th e backlight luminance in this case is varied according to the maximum gray level of the displayed image.…”

Section: Environmental Technologies and High-aperture-ratio Pixel Strmentioning

confidence: 99%

“…This method can reduce power consumption by about 8%. To further increase energy efficiency, the panel can be divided into segments, and the luminance of each segment can be controlled independently [78]. In the case of direct CCFL BLUs, which consist of many long fl orescence lamps located across the entire panel, and direct …”

Section: Environmental Technologies and High-aperture-ratio Pixel Strmentioning

confidence: 99%

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Technical evolution of liquid crystal displays

2009

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I n 1888, more than a century ago, the Austrian botanist FriedrichReinitzer discovered an intermediate state of matter between isotropic liquid and lattice-structured crystal [1][2][3]. Th is state, later termed liquid crystal (LC), remained merely a novelty for many years until suitable applications for the technology began to become apparent. From the late 1960s, following the realization that various display applications were possible, the popularity of liquid crystal as a research fi eld expanded rapidly, attracting the interest of many scientists who made fundamental contributions to the technologies that have led to the spectacular success of liquid crystal displays (LCDs) [3][4][5][6][7][8][9][10][11][12][13]. Th e development of the twisted nematic (TN) [4] and supertwisted nematic (STN) [5] cell confi gurations, along with the necessary manufacturing technologies [6][7][8][9], resulted in the birth of the LCD industry in the late 1970s and early 1980s. The subsequent development of thin-film transistor (TFT) technology provided a further boost to the industry in the late 1980s [14,15]. Th e boom was signifi cantly supported by the advancement of material technologies such as the highly reliable manufacturing of liquid crystal base materials, and the development of polymers for the alignment layer, color fi lter materials, and sheet-type polarizers formed from the poly(vinyl alcohol)-iodine complex.In the 1990s, LCDs occupied an important position in the display market primarily through notebook applications, although the cathode ray tube (CRT) continued to dominate the desktop monitor and television markets. Th e plasma display panel (PDP), which appeared in the commercial market in 1997, pioneered the large-area fl at panel display market. It was widely predicted at the time that PDPs would maintain the lead in the large-area display market and that LCDs in small-display information technology (IT) applications would soon be replaced by new technologies such as displays based on organic light-emitting diodes (OLEDs) [16,17]. Such predictions were based on the belief that the LCD technology suff ered from serious limitations in terms of both off -axis image quality and moving picture quality, and also that it had proved diffi cult to obtain reasonable manufacturing yields of large-area TFT panels. However, these predictions, as we now know, turned out to be incorrect. Th e application of LCDs has expanded rapidly in recent years from purely information technology (IT) applications to the television and mobile display markets, and now even to very-large-area digital information displays (DIDs).Interestingly, while LCDs penetrated the traditional territories of other display technologies including CRTs and PDPs, attracting inevitable and heavy competition from these technologies, the most critical competitors were in fact alternative LCD technologies. A range of LCD modes and technologies are now applied in the same areas of application and are compared directly with one another in the market. In applicat...

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Section: Environmental Technologies and High-aperture-ratio Pixel Strmentioning

confidence: 99%

Section: Environmental Technologies and High-aperture-ratio Pixel Strmentioning

confidence: 99%

Technical evolution of liquid crystal displays

2009

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“…When the BLC parameter is smaller than the maximum change of the block luminance which is called dimming level decision parameter ( κ ), the output PWM duty is tuned by (2). :…”

Section: Figure 5 Block Luminance Compensation Algorithmmentioning

confidence: 99%

“…Recently there has been a great deal of focus on local dimming LED backlights for high contrast ratio (CR), low power consumption, and wide color gamut [1][2][3]. However, this approach can induce various recognizable artifacts.…”

Section: Introductionmentioning

confidence: 99%

64.4: Smart Algorithms for Local Dimming LED Backlight

Yeo

Kwon

Kang

et al. 2008

Symp Digest of Tech Papers

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To reduce power consumption and improve image quality including contrast ratio and color gamut, LED backlight units (BLUs) consisting of many small blocks in 2-dimensional space are implemented. Either white-gray-level luminance or color is controlled by the local dimming LED BLU. However, such a BLU can induce various recognizable artifacts. A method is proposed for exact block luminance calculation along with a new algorithm to correct local dimming artifacts. A new concept of color classes has also been developed to achieve extremely wide color gamut and to minimize color related artifacts.

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“…However, edge-lit BLUs have shown weakness compared with direct-lit BLUs. Direct-lit BLUs have provided significant reduction of power consumption and meaningful improvement of the contrast ratio, by applying the local dimming technology [24], [25]. There have been technical reports on corresponding technologies for the edge-lit BLUs by individually controlling the luminance of the LEDs arranged in a row along the edges of an LGP [26], [27].…”

Section: Introductionmentioning

confidence: 99%

Effects of Light-Emitting Diode (LED) Configuration on Luminance and Color of an Edge-Lit Backlight Unit

Moon

2015

J. Display Technol.

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In this paper, we evaluated quantitative changes in the luminance and the color on the light-exit plane of an LED edge-lit backlight unit (BLU) by systematically controlling the optical properties of individual white LEDs. We placed a light absorbing film and red-green-blue filters to control the white intensity and the color of an individual LED string, respectively. Impacts of this 'defect' LED's optical properties were systematically monitored across the light-exit plane in terms of local distribution of the luminance and the color, overlaying prism films and diffusion film on a light guiding plate (LGP). The roles of prism films and diffusion film were also experimentally analyzed to assess their homogenizing capability for the luminance and the color with respect to the defect-like LEDs.

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

Cited by 65 publications

References 2 publications

Technical evolution of liquid crystal displays

Technical evolution of liquid crystal displays

64.4: Smart Algorithms for Local Dimming LED Backlight

Effects of Light-Emitting Diode (LED) Configuration on Luminance and Color of an Edge-Lit Backlight Unit

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