Browsing by Author "Shieh, HPD"

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3-D mobile display based on dual-directional light guides with a fast-switching liquid-crystal panel
(2005-10-01)
Chu, YM
;
Chien, KW
;
Shieh, HPD
;
Chang, JM
;
Hu, A
An autostereoscopic display based on dual-directional light guides with a fast-switching liquid-crystal panel was designed and fabricated to provide better 3-D perception with image qualities comparable to that of 2-D displays. With two identical micro-grooved light guides, each with a light-controlled ability in one direction, two restricted viewing cones are formed to project pairs of parallax images to the viewer's respective eyes sequentially. Crosstalk of less than 10% located within +/- 8 degrees-+/- 30 degrees and an LC response time of 7.1 msec for a 1.8- in. LCD panel can yield acceptable 3-D perceptions at viewing distance of 5.6-23 cm. Moreover, 2-D/3-D compatibility is provided in this module.
A method to enhance the data transfer rate of eutectic Sb-Te phase-change recording media
(2005-07-15)
Yeh, TT
;
Hsieh, TE
;
Shieh, HPD
;
材料科學與工程學系
;
光電工程學系
This work describes the effect of nitrogen doping to eutectic Sb-Te phase-change materials in order to enhance the speed of the amorphous-to-crystalline phase transformation. When nitrogen at a sputtering gas flow ratio of N-2/Ar=3% was doped in the eutectic Ge-In-Sb-Te recording layer, the data transfer rate was increased up to 1.6 times. When thin GeNx nucleation promotion layers were further added in below and above the recording layer, an overall enhancement up to 3.3 times in data transfer rate was achieved. The nitrogen contents corresponding to the N-2/Ar flow ratios (N-2/Ar=0%-10%) were calibrated by electron spectroscopy for chemical analysis. Transmission electron microscopy revealed that nitrogen doping was able to promote the phase transformation by generating numerous nucleation sites uniformly distributed in the recording layer and hence increased the recrystallization speed. (c) 2005 American Institute of Physics.
A method to enhance the data transfer rate of phase change recording media
(2004)
Yeh, TT
;
Hsieh, TE
;
Shieh, HPD
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Nitrogen doping was applied to enhance the velocity of amorphous-crystalline phase transformation. The nitrogen doping was able to produce tiny nitride precipitates uniformly distributed in the recording layer and provided numerous preferential sites for amorphous-crystalline transition. At the doping condition of N-2/Ar ratio = 3%, the recrystallization velocity of GeInSbTe phase change recording media was increased up to 1.6 times without severely damaging the signal jitter values.
A new illumination optical system for liquid crystal projectors
(1997)
Chang, CM
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Lin, KW
;
Chen, KV
;
Shieh, HPD
;
交大名義發表
A high efficient illumination optical system is designed to generate;In uniform and rectangular light source for liquid crystal light valve projectors. A short are and an optimized reflector design enable the total system to be highly efficient while a rectangular-pillar-like glass rod is used to transform a circular beam into a uniform and rectangular cross-section one. The optical system from the light source through the projection optimized to achieve optical efficiencies of 57% and uniformity of 70%.
A novel current memory circuit for AMOLEDs
(2004-06-01)
Lin, YC
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
A novel switched-current (SI) memory circuit with improved accuracy and operating frequency for active-matrix organic light-emitting displays (AMOLEDs) was developed. The proposed SI memory, constructed from current memory structure, can not only reduce the influence of charge-injection without using-larger storage capacitor, but also realize the significant amount of speed up by means of small storage capacitor. Furthermore, the capability of copying the current signal is achieved without relying on the matching of device characteristics. The proposed SI memory circuit was implemented by low temperature poly-silicon technology and is suitable for current driving scheme-based high-resolution AMOLED applications.
A novel current-scaling a-Si : H TFTs pixel electrode circuit for AM-OLEDs
(2005-06-01)
Lin, YC
;
Shieh, HPD
;
Kanicki, J
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光電工程學系
;
Department of Photonics
Hydrogenated amorphous silicon thin-film transistor (a-Si:H TFT) pixel electrode circuit with a function of current scaling is proposed for active-matrix organic light-emitting displays (AM-OLEDs). In contrast to the conventional current mirror pixel electrode circuit, in this circuit a high data-to-organic light-emitting device (OLED) current ratio can be achieved, without increasing the a-Si:H TFT size, by using a cascade structure of storage capacitors. Moreover, the proposed circuit can compensate for the variations of TFT threshold voltage. Simulation results, based on a-Si:H TFT and OLED experimental data, showed that a data-to-OLED current ratio larger than 10 and a fast pixel programming time can be accomplished with the proposed circuit.
A novel dual focus objective lens for DVD/CD pick-up head
(1998-03-01)
Liu, PY
;
Shieh, HPD
;
Ju, JJ
;
Tsai, ST
;
Yang, TM
A new dual focus objective lens of combinig aspherical surfaces of DVD and CD for DVD/CD pick-up head was designed. Numerical analysis based on the diffraction model were studied to trade off the spot size, side lobe, and energy ratio of DVD and CD, The hybrid aspherical surfaces of DVD and CD are optimized for low aberration. The spot size of full wave half maximum (FWHM) are 0.553 and 0.88 mu m for DVD and CD, respectively, measured from thus constructed double rings lens.
Analyses and improvements of whiteness of reflective liquid crystal displays
(2004-09-01)
Huang, YP
;
Chu, LS
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Shieh, HPD
;
光電工程學系
;
Department of Photonics
A reflective liquid crystal display (R-LCD) has become an important component of a portable information device; however, its inadequate whiteness appearance is a major issue in achieving the potential of "electronic paper". The factors causing inadequate whiteness were examined using a conventional R-LCD. Furthermore, a novel reflectance-profile-controlled component "random grating light control film" and a non dispersed LC mode with a high-cell-gap tolerance were presented to achieve the paper-white image of reflective LCDs.
Analyses of the operation of in-plane switching display mode of liquid crystal display
(1997)
Yoo, JC
;
Lin, KW
;
Shieh, HPD
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交大名義發表
;
光電工程學系
The IFS mode of LCD has wide viewing angle compared with TN mode, but requires a higher driving voltage to reach a maximum transmittance. The electro-optical properties of TPS mode are complicated and can not be fully revealed by an analytic form. In this letter, the electro-optical properties of in-plane switching mode mere analyzed by LC continuum theory to achieve a maximum transmittance at a low operating voltage.
Analysis of capacitance-voltage characteristics for two-dimensional multi-conductor in liquid crystal displays
(1996-04-22)
Lin, KW
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Shieh, HPD
;
Su, FCD
;
光電工程學系
;
Department of Photonics
The capacitance voltage characteristics for the two-dimensional multi-conductor in liquid crystal displays (LCDs) are numerically derived by the method of successive over relaxation (SOR). The nonlinear and anisotropic properties of dielectric constant in the LC cell depend on the orientation of LC molecules under the influence of inhomogeneous electric field. An LC continuum theory implemented by tensor takes elastic anisotropy and inhomogeneous electric field into consideration to calculate the two-dimensional molecule orientations and potential distribution in LCDs. The dependence of capacitance on applied voltages and the geometric of LC cell is quantitatively described, Nonlinear capacitance results in capacitive coupling which causes flicker and adversely degrades image retention in LCD. (C) 1996 American Institute of Physics.
Analysis of the operation of mixed-mode twisted nematic cells
(1997-01-01)
Lin, KW
;
Yoo, JC
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Shieh, HPD
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光電工程研究所
;
Institute of EO Enginerring
Analysis of mixed-mode twisted nematic (MTN) cells in one- and two-dimension simulation are presented. Two-dimensional simulation reveals that the light leakage in the region of the reverse tilt domain in MTN cells reduces the contrast ratio with a novel method by adding a bias voltage onto Silicon substrates, the light leakage can be suppressed and the open ratio of the cell is greatly improved.
Analysis of the operation of mixed-mode twisted nematic cells
(1997-01-01)
Lin, KW
;
Yoo, JC
;
Shieh, HPD
;
交大名義發表
;
光電工程學系
Analysis of mixed-mode twisted nematic (MTN) cells in one- and two-dimension simulation are presented. Two-dimensional simulation reveals that the light leakage in the region of the reverse tilt domain in MTN cells reduces the contrast ratio with a novel method by adding a bias voltage onto Silicon substrates, the light leakage can be suppressed and the open ratio of the cell is greatly improved.
Applications of microtube array on transtlective liquid crystal displays for backlight efficiency enhancement
(2004-12-01)
Yang, YS
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Huang, YP
;
Shieh, HPD
;
Tsai, MC
;
Tsai, CY
A novel transflective liquid crystal display (LCD) with a microtube array structure to make the most effective use of backlight was demonstrated. By redefining the area ratio of transmissive and reflective regions, high light efficiency in both transmissive and reflective subpixels can be attained. Based on the principle of light collection, a simulation model was established to characterize the features and optimize the microtube array structure. Furthermore, a typical TFT-LCD process was utilized to fabricate the optimized structure. A prototype microtube array was fabricated, and the measured enhancement of backlight utilization efficiency can be as high as a factor of 1.81.
Applications of multidirectional asymmetrical microlens-array light-control films on reflective liquid-crystal displays for image quality enhancement
(2004-06-20)
Huang, YP
;
Shieh, HPD
;
Wu, ST
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光電工程學系
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Department of Photonics
The multidirectional asymmetrical microlens-array light-control film (MAMA-LCF) is developed for enhancing the image brightness and contrast ratio of various reflective liquid-crystal displays. By use of index-matching material, the interface reflection is greatly reduced. Through optimized designs, the surface-scattering effect is also suppressed; thus the contrast ratio is much enhanced. From experimental results, the MAMA-LCF leads to a similar to1.5x gain in brightness over the MgO standard white and a 15:1 contrast ratio for the reflective color super-twist nematic liquid-crystal display, 2.8x MgO and a 23:1 contrast ratio for the polymer-dispersed liquid-crystal, and 2.8x MgO and a 13:1 contrast ratio for the cholesteric liquid-crystal display. Potential applications of this low-cost plastic thin film for reflective liquid-crystal displays are foreseeable. (C) 2004 Optical Society of America.
Brightness and contrast enhancement of reflective liquid crystal displays by microlens array light control film
(2000-05-01)
Ko, FJ
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
An off-axis microlens array light control film (OMA-LCF) for brightness and contrast enhancement in reflective liquid-crystal displays (LCDs) is demonstrated. The OMA-LCF is constructed with an off-axis microlens array (with a half-lens body) and then laminated to the top surface (toward the viewer) of the uppper glass of the reflective LCDs. The filmlike device directs incident light to a reflected cone with a controlled angular profile nearly normal to the display surface, yields a gain of about 1x to 10x of MgO standard-white in the typical viewing region from 0 degrees to 20 degrees. Moreover, glare and optical losses can be greatly reduced.
Carrier-to-noise ratio improvement with pulsed-laser readout on magnetically induced superresolution by center aperture detection disks
(1999-09-01)
Chen, BM
;
Yang, BW
;
Hwang, WK
;
Shieh, TE
;
Shieh, HPD
Magnetically induced superresolution by center aperture detection (MSR-CAD) using pulsed and conventional de schemes were applied to magneto-optical disks to quantitatively evaluate readout performances. By simulation and experiments, it was found that carrier-to-noise ratio (CNR) in the pulsed-laser readout was about 2.5 dB higher than that in the de readout scheme at mark size of 0.45 mu m or shorter, Therefore, pulsed readout is feasible to improve CNR and recording density in MSR-CAD disks.
Center aperture detection on magnetically induced super resolution magneto-optical disks
(1996-03-01)
Liu, PY
;
Shieh, HPD
;
交大名義發表
;
光電工程學系
;
National Chiao Tung University
A vector diffraction model has been applied to analyze CAD readout of MSR disks. Numerical results indicate that the read power is optimized with an aperture of the same size as the recorded mark. CNR decreases as recorded density increases even by using optimized aperture. CAD MSR disks applications are limited by the aperture-to-spot ratio of 34%. Also, CNR decreases as the track pitch becomes narrower. The vector model presents a higher sensitivity than the scalar model in analyzing the optical readout characteristics of sub-mu m disk structure and 'below-diffraction-limit' aperture of the readout spot.
Color characterization of an LC projection system using multiple-regression matrix and look-up-table with interpolation
(1998)
Liaw, MJ
;
Chen, CY
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
A forward model of an LC projector is studied to predict its colorimetric attribution. To identify color characteristics of the projector, 729 colors were measured in a dark room. The forward model was built using three methods: (I) a 3x11 multiple-polynomial regression matrix, (2) a 3-dimensional(3-D) look-up table(LUT) viith cubic interpolation, and (3) a one dimensional(I-D) LUT with linear interpolation. In addition, 216 colors were also measured to evaluate the prediction accuracy of the forward model. All methods can be used to obtain acceptable predictions of calorimetric attributions on the LC projector. When the 3x11 multiple-polynomial regression matrix was used, the average and maximum prediction differences were 2.18 and 6.68 Delta E-uv*, respectively. For the 3-D LUT method, those values were 3.3 and 16.4 Delta E-uv*, respectively. The results of the 1-D LUT are comparable with those of the 3-D LUT if die sampling points per channel of these two approaches are the same. If the sampling points per channel are dense enough, for example 16 points per channel, the performance of the I-D LUT is better than that of the 3x11 multiple-polynomial regression matrix.
Color characterization of twist nematic LC panels by using empirical functions
(1998)
Liaw, MJ
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Shieh, HPD
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光電工程學系
;
Department of Photonics
An empirical exponential equation is proposed to characterize the transfer functions of the image signals to tristimulus values of twist nematic (TN) liquid crystal displays(CDs). Parameters of the empirical equation can be determined according to the colorimetric measurements of the test panel without knowing the panel's physical details. A two-stage forward model is also proposed to model the color characteristics of TN LCDs by using the empirical function. Moreover, a backward model is derived to reproduce desired colors accurately on TN LCDs. The main benefit of the study is that only 12 colors should be measured to characterize color rendering on TN LCDs.
Color rendering of cathode ray tube (CRT) by digital driving
(1997-08-01)
Liaw, MJ
;
Shieh, HPD
;
光電工程研究所
;
Institute of EO Enginerring
Color rendering by digital driving methods of equal voltage change (EVC) and equal color difference (ECD) were studied. A CRT was assumed to be driven by 262,144 (64 x 64 x 64) RGB digital combinations. The number of ''effective'' colors which can be discriminated one another were calculated. It reveals that ECD supports more digital combinations (78.9% for ECD and 68.0% for EVC, respectively) to produce effective colors. ECD driving also supports higher color resolution except in the region of color gamut with lightness value below 20. In the dark region, EVC supports higher color resolution. Color images can be shown with higher fidelity by choosing proper digital driving methods.