Browsing by Author "Wei, Ching-Ming"

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A Color Break-Up Suppression Method, Stencil-FSC Method, for Field-Sequential-Color(FSC) LCDs with low Power Consumption
(2008)
Huang, Yi-Pai
;
Lin, Fang-Cheng
;
Wei, Ching-Ming
;
Shieh, Han-Ping D.
;
Tsai, Chi-Chung
Field sequential color liquid crystal display (FSC-LCDs) is a display without color filter, so it achieves several attractive advantages. However, it has a serious issue called color breakup (CBU), which degrades image quality and causes viewers uncomfortable. Consequently, the "Stencil-FSC" method, which utilized multi-color image in a single field, was proposed to suppress CBU. Moreover, optimizations of hardware parameters were done to get the optimal CBU suppression. Finally, the Stencil-FSC method was successfully demonstrated on a 32-inch FSC-LCD with effectively suppressed CBU, resulting contrast ratio of more than 5,500:1, and average power consumption of less than 45 Watt.
A human visual model for color break-up artifact in design field-sequential color LCDs
(2007)
Chen, Sheng-Chang
;
Yan, Shu-Ping
;
Cheng, Yu-Kuo
;
Lin, Fang-Cheng
;
Wei, Ching-Ming
A model to evaluate the color break-up (CBU) of field-sequential color liquid crystal display (FSC-LCD) had been successfully established. In order to quantify the CBU, "Color Break-Up Angle (CBUA)" was proposed as the evaluation index. From the psychophysical experiments, the CBUA=0.26 degrees was reported as the averaged threshold value for indistinguished color break-up. Consequently, the minimum frame rate could be derived from the model to suppress CBU in the various FSC-LCDs.
A visual model of color break-up for design field-sequential LCDs
(2007)
Yan, Shu-Ping
;
Cheng, Yu-Kuo
;
Lin, Fang-Cheng
;
Wei, Ching-Ming
;
Huang, Yi-Pai
A model to evaluate the color break-up (CBU) of field-sequential color liquid crystal display (FSC-LCD) had been successfully established. In order to quantify the CBU, "Color Break-Up Angle (CBUA)" was proposed as the evaluation index. Front the psychophysical experiments. the CBUA=0.22 degrees was reported ass the averaged threshold value for indistinguished color break-up. Consequently, the minimum frame rate could be derived from the model to suppress CBU in the various FSC-LCDs.
Color Filter-Less LCDs in Achieving High Contrast and Low Power Consumption by Stencil Field-Sequential-Color Method
(2010-03-01)
Lin, Fang-Cheng
;
Huang, Yi-Pai
;
Wei, Ching-Ming
;
Shieh, Han-Ping D.
;
光電工程學系
The field-sequential-color liquid crystal display (FSCLCD) without a color filter enables high light efficiency, wide color gamut, and low material cost. However, the visual defect of color breakup (CBU) is perceived when relative velocities exist between the screen image and the human eye. We proposed the Stencil-FSC method with a 240-Hz field rate to make CBU imperceptible. Given the Stencil-FSC method, the hardware parameters were optimized to reduce hardware complexity while maintaining sufficient suppression of CBU. After implementing Stencil-FSC on a 32-in FSCLCD, the image contrast ratio was shown to be ten times more than that of a conventional CCFL LCD, and the average power consumption was reduced to less than 35 W-a 67% savings in power consumption.
Color-breakup suppression and low-power consumption by using the Stencil-FSC method in field-sequential LCDs
(2009-03-01)
Lin, Fang-Cheng
;
Huang, Yi-Pai
;
Wei, Ching-Ming
;
Shieh, Han-Ping D.
;
光電工程學系
Field-sequential color (FSC) is a potential technique for low-power liquid-crystal displays (LCDs). However, it still experiences a serious visual artifact, color break-up (CBU), which degrades image quality. Consequently, the "Stencil Field-Sequential-Color (Stencil-FSC)" method, which applies local color-backlight-dimming technology at a 240-Hz field rate to FSC-LCDs, is proposed. Using the Stencil-FSC method not only suppressed CBU efficiently but also enhanced the image contrast ratio by using low average power consumption. After backlight signal optimization, the Stencil-FSC method was demonstrated on a 32-in. FSC-LCD and effectively suppressed the CBU, which resulted in more than a 27,000:1 dynamic contrast ratio and less than 40-W average power consumption.
Enhancing thermoelectric performance by Fermi level tuning and thermal conductivity degradation in (Ge1-xBix)Te crystals
(2019-06-13)
Wei, Pai-Chun
;
Cai, Cheng-Xun
;
Hsing, Cheng-Rong
;
Wei, Ching-Ming
;
Yu, Shih-Hsun
In this work, a high thermoelectric figure of merit, zT of 1.9 at 740 K is achieved in Ge1-xBixTe crystals through the concurrent of Seebeck coefficient enhancement and thermal conductivity reduction with Bi dopants. The substitution of Bi for Ge not only compensates the superfluous hole carriers in pristine GeTe but also shifts the Fermi level (E-F) to an eligible region. Experimentally, with moderate 6-10% Bi dopants, the carrier concentration is drastically decreased from 8.7 x 10(20) cm(-3) to 3-5 x 10(20) cm(-3) and the Seebeck coefficient is boosted three times to 75 mu VK-1. In the meantime, based on the density functional theory (DFT) calculation, the Fermi level E-F starts to intersect with the pudding mold band at L point, where the band effective mass is enhanced. The enhanced Seebeck coefficient effectively compensates the decrease of electrical conductivity and thus successfully maintain the power factor as large as or even superior than that of the pristine GeTe. In addition, the Bi doping significantly reduces both thermal conductivities of carriers and lattices to an extremely low limit of 1.57W m(-1)K(-1) at 740 K with 10% Bi dopants, which is an about 63% reduction as compared with that of pristine GeTe. The elevated figure of merit observed in Ge1-xBixTe specimens is therefore realized by synergistically optimizing the power factor and downgrading the thermal conductivity of alloying effect and lattice anharmonicity caused by Bi doping.
Stencil-FSC method for color break-up suppression and low power consumption in field-sequential LCDs
(2008)
Lin, Fang-Cheng
;
Huang, Yi-Pai
;
Wei, Ching-Ming
;
Shieh, Han-Ping D.
;
Tsai, Chi-Chung
Field sequential color liquid crystal displays (FSC-LCDs) are still facing a serious artifact, colo break-up (CBU), which degrades image quality. Consequently, we propose the "Stencil-FSC" method, applying local color-backlight dimming technology to FSC-LCDs with a 240 Hz field rate which not only suppresses CBU efficiently but also enhances the contrast ratio of images in using ultralow average power consumption. The Stencil-FSC method was demonstrated on a 32-inch FSC-LCD and effectively suppressed CBU, resulting contrast ratio of more than 5,500:1, and average power of less than 45 Watt.
Thermoelectric Figure-of-Merit of Fully Dense Single-Crystalline SnSe
(2019-03-01)
Wei, Pai-Chun
;
Bhattacharya, Sriparna
;
Liu, Yu-Fei
;
Liu, Fengjiao
;
He, Jian
Single-crystalline SnSe has attracted much attention because of its record high figure-of-merit ZT approximate to 2.6; however, this high ZT has been associated with the low mass density of samples which leaves the intrinsic ZT of fully dense pristine SnSe in question. To this end, we prepared high-quality fully dense SnSe single crystals and performed detailed structural, electrical, and thermal transport measurements over a wide temperature range along the major crystallographic directions. Our single crystals were fully dense and of high purity as confirmed via high statistics Sn-119 Mossbauer spectroscopy that revealed < 0.35 at. % Sn(IV) in pristine SnSe. The temperature-dependent heat capacity (C-p) provided evidence for the displacive second-order phase transition from Pnma to Cmcm phase at T-c approximate to 800 K and a small but finite Sommerfeld coefficient gamma(0) which implied the presence of a finite Fermi surface. Interestingly, despite its strongly temperature-dependent band gap inferred from density functional theory calculations, SnSe behaves like a low-carrier-concentration multiband metal below 600 K, above which it exhibits a semiconducting behavior. Notably, our high-quality single-crystalline SnSe exhibits a thermoelectric figure-of-merit ZT similar to 1.0, similar to 0.8, and similar to 0.25 at 850 K along the b, c, and a directions, respectively.