Browsing by Author "Chen, Szu-Fen F."

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CSD-A New Unified Threshold Metric of Evaluating LCD Viewing Angle by Color Saturation Degradation
(2006-06-01)
Chen, Szu-Fen F.
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Cheng, Wei-Chung W.
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Shieh, Han-Ping D.
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光電工程學系
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顯示科技研究所
Lower luminance contrast ratio and chromatic changes affect the visual performance (i.e. color shift) of a thin-film transistor liquid-crystal device (TFT-LCD) at large viewing angles. The de facto method of defining viewing angle, contrast ratio of luminance, fails to represent the substantial visual performance viewed at a larger angle. We found the degradation of color saturation, dS*/d theta, to be an appropriate metric to aid the conventional viewing angle definition (CR >= 0). We empirically determined the threshold for defining the color viewing angles of TFT-LCDs, CVA = {theta parallel to dS*/d theta vertical bar <= 0.03} which reflects the variation not only in chromaticity but also in luminance. The proposed metric was evaluated by psychophysical experiments, whose results validate the efficacy of the proposed metric.
Design and fabrication of transflective cholesteric LCD with image enhanced reflector
(2005)
Huang, Chao-Heng
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Huang, Yi-Pai
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Chen, Szu-Fen F.
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Shieh, Han-Ping D.
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光電工程學系
A novel transflective liquid crystal display is demonstrated by using cholesteric liquid crystal as a LC layer and an image-enhanced reflector (IER) on the top of the transmissive sub-pixel, providing the similar paths for both reflected and transmitted light, and two circular polarizers laminated on the upper and rear substrates. An extended IER (EIER) is applied to enhance the brightness and CR. As a result, Ch-LCD displays the same image color in any ambience, thus greatly improve the image quality of the transflective cholesteric LCD.
High video image quality technology: Dynamic scanning backlight with black insertion (DSBBI) implemented in a 32 '' OCB-LCD TV
(2007-01-01)
Hsu, Tien-Chu P.
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Cheng, Jung-Chieh L.
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Hsu, Ming-Tan T.
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Chen, Szu-Fen F.
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光電工程學系
"Dynamic Scanning Backlight with Black Insertion" method was proposed to enhance video image quality This method utilizes the dynamic backlight luminance control to increase contrast and the scanning backlight with black insertion to reduce MPRT This technology was successfully implemented in a 32 " OCB-LCD TV As the results, the DSBBI technology increased contrast ratio over 1000:1, and reduced the MPRT less than 6ms.
Splay-to-Bend Transition-Free Reactive Monomer Modified Pi-Cell
(2009-05-01)
Chen, Szu-Fen F.
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Chen, Huang-Ming P.
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Chow, Liansing
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Chang, Yu-Yun
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Shieh, Han-Ping D.
A reactive monomer modified Pi-cell (RMM-Pi-cell) comprising a layer of liquid crystal (LC) reactive monomer on one surface was prepared to control the surface pretilt angle. The simulation results suggested that a transition-free Pi-cell can be prepared by asymmetrical cell with one 8 degrees pretilt angle and the other surface greater than 47 degrees when the cell gap was smaller than 4 mu m. The nematic reactive monomer layer has a molecular average tilt angle over 80 degrees which allowed the LC molecules to be arranged in a favored bend state in the asymmetrical cell. The critical voltages cannot be found in all 3-mu m RMM-Pi-cells. The cell retardation data confirmed the initial bend orientation with zero voltage applied. Moreover, the light leakage of dark state was reduced. The contrast ratio of RMM-Pi-cell was improved by a factor of 11 compared with an original Pi-cell without using compensation film.
Transition Free, High Contrast Reactive Monomer Modified Pi-Cell
(2009)
Chen, Szu-Fen F.
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Chang, Yu-yun
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Chow, Liansing Culp
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Chen, Huang-Ming Philip
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Shieh, Han-Ping D.
The proposed reactive monomer modified Pi-cell (RMM-Pi-cell) can suppress its critical voltage to zero, i.e. state transition free cell. The cell retardation data confirmed the initial bend orientation with zero voltage applied. The additional nematic reactive monomer (RM) layer possessed molecular average tilt angle over 80 degrees which allowed the liquid crystal molecules arranged in favored bend state in 3 mu m cell. Moreover, the light leakage of dark state was reduced. The contrast ratio of RMM-Pi-cell was improved by a factor of 11 compared with an original Pi-cell without using compensation film.