Browsing by Author "Chen, Cheng-Huan"

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A Light Guide Plate That Uses Asymmetric Intensity Distribution of Mini-LEDs for the Planar Illuminator
(2019-03-08)
Ye, Zhi-Ting
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Pai, Yung-Min
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Chen, Cheng-Huan
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Kuo, Hao-Chung
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Chen, Lung-Chien
Traditional backlights are designed with new dot patterns, and then injection molding, laser beam fabrication, or UV (Ultraviolet) roll-to-plate imprinting is used to apply dot patterns to a light guide plate-the process consumes considerable time and resources. Therefore, we propose a novel light guide design that does not use a dot pattern. We designed an asymmetric intensity distribution of mini-LEDs (Light Emitting Diode) and a light guide plate with a fully printed diffusion reflection on the bottom surface for a planar illuminator. The design rules for the proposed architecture are described in this paper. The archetype design with a 152.4 mm circular down-light has a diameter of 143 mm for the planar light source module. The experiment achieved a total efficiency of 85% and uniformity of 92.6%.
Color separation system with angularly positioned light source module for pixelized backlighting
(2010-01-18)
Chen, Po-Chou
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Lin, Hui-Hsiung
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Chen, Cheng-Huan
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Lee, Chi-Hung
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Lu, Mao-Hong
A color-separation system that angularly positions color LEDs to produce color separation and a lens array to focus this light onto the pixels is proposed. The LED rays from different incident angles are mapped into corresponding sub-pixel positions to efficiently display color image, which can be used to replace the absorbing color filter in the conventional liquid crystal layer. In this paper, the prototype backlight has been designed, fabricated and characterized. The measurement results of this module showed that a gain factor of transmission efficiency three times more than that of conventional color filters efficiency improvement and a larger color gamut are expected. (C)2010 Optical Society of America
Direct View and Projection Switchable Mobile Display
(2009-01-01)
Huang, Hsin-Hsuan
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Chen, Cheng-Huan
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Lai, Yu-Cheng
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Chang, Yu-Cheng
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Huang, Yi-Pai
The function of mobile phone becomes more versatile as a personal assistant. In order to make display device optimized for different function of the mobile phone, this paper proposes a display device which can be switched among 2D direct view, 3D direct view and projection modes while using single liquid crystal(LC) panel as image source. The device features a highly collimated backlight unit and polymer dispersed liquid crystal(PDLC) diffuser at the back of the LC panel, and a switchable lenticular array as well as a stretchable projection lens in front. The ray tracing simulation has shown well controlled light path of the backlight module and sufficient image quality of the projection lens while maintaining the compactness of the device for mobile application.
Dual-focal-plane augmented reality head-up display using a single picture generation unit and a single freeform mirror
(2019-07-10)
Qin, Zong
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Lin, Shih-Ming
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Lu, Kuang-Tso
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Chen, Cheng-Huan
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Huang, Yi-Pai
Two or more focal planes are required in augmented reality head-up displays (AR HUDs) to respectively present basic and interactive driving information to car drivers; whereas, solutions using two separated picture generation units (PGUs) with two sets of optics incur increased cost, reduced reliability, and expanded volume. To develop an AR HUD using a single PGU and a single curved mirror, we propose to set two logically separated regions on a single PGU and optically relay one of them to a new position to create two focal planes. A single freeform mirror acquired through careful optical and mechanical design optimization produces high image quality in an eyebox of 120 mm by 60 mm, simultaneously for a far image (9 m, 10 degrees by 3 degrees) and a near image (2.5 m, 6 degrees by 2 degrees). Finally, an AR HUD product with a compact volume of 8.5 L is fabricated to experimentally verify the design. (C) 2019 Optical Society of America
Enhancing the Light-Extraction Efficiency of AlGaN-Based Deep-Ultraviolet Light-Emitting Diodes by Optimizing the Diameter and Tilt of the Aluminum Sidewall
(2018-11-01)
Pai, Yung-Min
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Lin, Chih-Hao
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Lee, Chun-Fu
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Lin, Chun-Peng
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Chen, Cheng-Huan
To realize high-efficiency AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs), enhancing their light-extraction efficiency (LEE) is crucial. This paper proposes an aluminum-based sidewall reflector structure that could replace the conventional ceramic-based packaging method. We design optimization simulations and experimental results demonstrated the light power output could be enhanced 18.38% of DUV-LEDs packaged with the aluminum-based sidewall.
High transmittance LC pixel design for multi-view 3D mobile display
(2008)
Mphepoe, Wallen
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Wu, Chi-Lin
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Huang, Yi-Pai
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Chuang, Shang-Chih
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Chen, Cheng-Huan
Using a 6-view 3D mobile display, a modified LC pixel mode that increases transmittance and brightness uniformity for each viewing zone plus pixel electrode physical re-configuration capable of increasing Aperture Ratio were investigated The pixel mode utilized was the single-domain VA. In the modified case of the single domain VA mode with the reconfiguration, it was observed that by optimizing each pixel, the transmittance of the single-domain VA could be improved by more than 24% at relatively wide, mobile display, viewing angles from similar to 9 degrees to similar to 30 degrees compared with conventional multi-domain VA.
Holographic Line Beam Scanner with Liquid Crystal on Silicon Modulator
(2014-01-01)
Chen, Jian-Tsung
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Chen, Cheng-Huan
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Tsai, Chung-Li
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光電工程學系
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Department of Photonics
A laser scanning device can be used for contour or pattern reconstruction with associated image processing or recognition algorithm. For a better accuracy or accommodating to a high efficiency algorithm, the laser beam often needs reshaping to a specific pattern, such as a line beam, or homogenization so as to reduce the spatial variation of the device performance. In addition, a scanning mechanics is normally inevitable. Both beam shaping and scanning module take quite a volume in the whole system, which could be an issue for the applications in which miniature device is highly desired. In this paper, a holographic scanner has been proposed to perform both laser beam shaping and scanning function. A pure phase modulation liquid crystal on silicon (LCoS) device is used for implementing the dynamic hologram. The LCoS has a pixel size of 3.74 mu m, and provides 16 phase level with a full phase depth of 2 pi. A line beam with 20mm and uniformity up to 70% is generated and it is scanned back and forth in the orthogonal direction of the line with a stroke of 20mm. The scanning line pattern is generated based on iterative Fourier transform algorithm (IFTA) and the first diffraction order pattern is exploited with the zero order being blocked and absorbed so that the noise in the scanning line pattern is minimized. The proposed scheme is a compact and versatile solutions for patterned laser beam scanning devices.
Hybrid laser-beam-shaping system for rotatable dual beams with long depth of focus
(2016-10-01)
Chou, Fu-Lung
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Chen, Cheng-Huan
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Lin, Yu-Chung
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Lin, Mao-Chi
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光電工程學系
A laser processing system consisting of two diffractive elements and one refractive element is proposed enabling a Gaussian laser beam to be transformed into two beams with a depth of focus of up to 150 mu m and focal spot smaller than 5 mu m. For specific laser processing, the two beams are rotatable when the beam-splitting diffractive element is rotated. The overall system is versatile for laser cutting and drilling.
Hybrid laser-beam-shaping system for rotatable dual beams with long depth of focus
(2016-10)
Chou, Fu-Lung
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Chen, Cheng-Huan
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Lin, Yu-Chung
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Lin, Mao-Chi
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光電工程學系
A laser processing system consisting of two diffractive elements and one refractive element is proposed enabling a Gaussian laser beam to be transformed into two beams with a depth of focus of up to 150 mu m and focal spot smaller than 5 mu m. For specific laser processing, the two beams are rotatable when the beam-splitting diffractive element is rotated. The overall system is versatile for laser cutting and drilling.
Improvement of light quality by ZrO2 film of chip on glass structure white LED
(2016-01-25)
Lin, Huang-Yu
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Ye, Zhi-Ting
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Lin, Chien-Chung
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Chen, Kuo-Ju
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Tu, Hsien-Hao
A novel combination of blue LED chips, transparent glass substrates and phosphors with PDMS thin film is demonstrated. The flip-chip bonding technology is applied to facilitate this design. The ZrO2 nanoparticles are also doped into the PDMS film to increase light scattering. The resultant luminous efficiency shows an 11% enhancement when compared to the regular COG device. The variation of correlated color temperature of such devices is also reduced to 132K. In addition to these changes, the surface temperature is reduced from 121 degrees C to 104 degrees C due to good thermal dissipation brought by ZrO2 nanoparticles. (C) 2015 Optical Society of America
Liquid crystal panel for high efficiency autostereoscopic 3D displays
(2008-01-01)
Chuang, Shang-Chih
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Chen, Cheng-Huan
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Mphepoe, Wallen
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Wu, Chi-Lin
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Huang, Yi-Pai
This paper proposes a configuration of liquid crystal panel for 3D application with the viewing angle property of each pixel varied and optimized for the direction to the corresponding perspective view, and the light blocking area of each pixel is located in accommodation to the lenticular and barrier design. The simulation result shows better performance on efficiency and cross talk comparing to the similar 3D display using traditional liquid crystal panel with the same pixel count and pixel Size.
Liquid crystal panel for high efficiency barrier type autostereoscopic three-dimensional displays
(2009-06-20)
Chen, Cheng-Huan
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Huang, Yi-Pai
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Chuang, Shang-Chih
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Wu, Chi-Lin
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Shieh, Han-Ping D.
An autostereoscopic display with parallax barrier attached onto a liquid crystal panel suffers from the trade-off between brightness and crosstalk. One approach for making improvement by modifying the layout of light blocking components, such as thin film transistor, storage capacitor, and protrusion, in the liquid crystal pixel has been proposed. Ray tracing simulation shows that the aperture of the slanted barrier can be significantly increased, hence increasing efficiency, while keeping the same crosstalk level if those light blocking components can be shifted to the corner of the pixel. A six-view 2.83 in. (7.19 cm) prototype has shown improvement on both brightness and crosstalk compared to its counterpart using a traditional liquid crystal panel, which demonstrates an effective approach for a high-efficiency barrier-type autostereoscopic 3D display with a liquid crystal panel. (C) 2009 Optical Society of America
Liquid Type Nontoxic Photoluminescent Nanomaterials for High Color Quality White-Light-Emitting Diode
(2018-12-22)
Lin, Chih-Hao
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Pai, Yung-Min
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Lee, Chun-Fu
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Verma, Akta
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Lin, Huang-Yu
High-brightness white-light-emitting diodes (w-LEDs) with excellent color quality is demonstrated by using nontoxic nanomaterials. Previously, we have reported the high color quality w-LEDs with heavy-metal phosphor and quantum dots (QDs), which may cause environmental hazards. In the present work, liquid-type white LEDs composed of nontoxic materials, named as graphene and porous silicon quantum dots are fabricated with a high color rendering index (CRI) value gain up to 95. The liquid-typed device structure possesses minimized surface temperature and 25% higher value of luminous efficiency as compare to dispensing-typed structure. Further, the as-prepared device is environment friendly and attributed to low toxicity. The low toxicity and high R9 (87) component values were conjectured to produce new or improve current methods toward bioimaging application.
MICRO OPTICAL PICKUP APPARATUS
(2009-10-08)
Chen, Cheng-Huan
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Su, Ya-Ni
This invention discloses a micro optical pickup apparatus for providing an incident light to an optical recording medium, receiving a reflected light from the optical recording medium, and thereby accessing data of the optical recording medium. The micro optical pickup apparatus includes a light source generating element for producing the incident light, an axial light splitting element allowing the incident light to pass through and deflecting the reflected light according to polarization directions of the incident and reflected lights, a polarization element disposed between the axial light splitting element and the optical recording medium is capable of changing the polarization directions of the incident light and reflected light of the optical recording medium, an astigmatic mirror for receiving, astigmatism focusing and reflecting the reflected light from the axial light splitting element, and an optical sensing element for receiving the reflected light from the astigmatic mirror and converting the reflected light into a corresponding electric signal.
Near-infrared imaging system for nondestructive inspection of micro-crack in wafer through dicing tape
(2015-10-01)
Lin, Sheng-Feng
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Chen, Cheng-Huan
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Lo, Cheng-Yao
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光電工程學系
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顯示科技研究所
Detection of wafer/die crack after the wafer dicing process is important for yield rate control prior to packaging. The traditional approach of microscopic examination is done after the dies are stripped from the dicing tape, and further crack propagation could result from this pick-and-place process. An on-tape crack inspection technique is proposed in this paper so that the crack from the dicing process can be clearly identified. The issues of seeing through the silicon substrate and the scattering at the dicing tape have been resolved, respectively, using a near-infrared wavelength of 1100 nm for illumination and using a feeding index matching liquid for filling the rough surface of the tape. Both the illumination and imaging optics of the inspection system have been designed and simulated with a ray-tracing program, and the prototype demonstrates the ability of seeing through the silicon substrate and dicing tape as well as detecting micro-crack down to 1.25 mu m, whose resolution is sufficient for most applications of die crack inspection. (C) 2015 Optical Society of America
Nondestructive Optical Inspection System for the Dicing Street Quality of Copper/Low-k Wafer
(2015)
Lin, Sheng-Feng
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Chen, Cheng-Huan
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Lo, Cheng-Yao
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光電工程學系
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顯示科技研究所
To resolve the issue in detecting sidewall crack defect mode in the die singulation of copper/low-k wafer after laser pre-groove/cleaning process, we combine a dedicated optical system with automatic optical inspection system in the production line for the nondestructive wafer-by-wafer optical inspection system to inspect the dicing street quality of copper/low-k wafer. Experiment shows that the sidewall crack defect can be clearly identified with the proposed inspection system and it is potentially applicable for the production line.
Novel Method for Estimating Phosphor Conversion Efficiency of Light-Emitting Diodes
(2018-12-01)
Lin, Chih-Hao
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Huang, Che-Hsuan
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Pai, Yung-Min
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Lee, Chung-Fu
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Lin, Chien-Chung
This study presents a novel method for estimating the phosphor conversion efficiency of white light-emitting diodes (WLEDs) with different ratios of phosphors. Numerous attempts have been made for predicting the phosphor conversion efficiency of WLEDs using Monte Carlo ray tracing and the Mie scattering theory. However, because efficiency depends on the phosphor concentration, obtaining a tight match between this model and the experimental results remains a major challenge. An accurate prediction depends on various parameters, including particle size, morphology, and packaging process criteria. Therefore, we developed an efficient model that can successfully correlate the total absorption ratio to the phosphor concentration using a simple equation for estimating the spectra and lumen output. The novel and efficient method proposed here can accelerate WLED development by reducing costs and saving fabrication time.
One-Dimensional Reflective Diffuser for Line Beam Shaper with Microlens Array Homogenizer
(2014-09-01)
Hsiao, Yung-Neng
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Wu, Hau-Ping
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Chen, Cheng-Huan
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Lin, Yu-Chung
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Lee, Min-Kai
A laser beam shaping architecture based on a microlens array homogenizer has been exploited, in which the interference effect due to the coherency of the laser source deteriorates the uniformity. Moving diffusers have been considered as an effective way of averaging out the interference pattern. Because the uniformity is required in the line direction only, a one-dimensional reflective-type diffuser with a well-controlled diffusion angle has been proposed and prototyped. The diffuser is attached onto a rotating cylinder for movement in operation. The experiment demonstrates the effectiveness of the scheme, and a line beam with a uniformity of up to 92% has been achieved. (C) 2014 The Japan Society of Applied Physics
Optical and thermal design of light emitting diodes omnidirectional bulb
(2015-10-01)
Ye, Zhi Ting
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Kuo, Hao-Chung
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Chen, Cheng-Huan
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光電工程學系
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Department of Photonics
The penetration of LED light bulbs into the lighting market is growing quickly in recent years due to significant increase of LED efficiency and reduction of cost. One major issue to be improved is the overall light bulb efficiency, which can fulfill "Energy Star for Lamps" while keeping sufficiently high efficiency. The efficiency issue results mainly from the high directionality of the LED sources and the corresponding solutions to make the emission more diverse. In this paper, a diffusion white reflection sheet (DWRS) with an array of holes is proposed as a high efficiency solution for modulating a light emission profile with SMD type LED source. The hole size is adjusted with fixed hole pitch to both maximize the efficiency and meet the omnidirectional specification. In addition, the concept of thermal plastic insertion molding metal is proposed for thermal management without fins for cooling. The prototype demonstrates the efficiency (Ef.) of 87.6% and LED pad temperature of 85 degrees C, which shows the feasibility as a total solution for high efficiency LED omnidirectional bulbs. (C) 2015 Optical Society of America
Optical Design of Compact Space Autonomous Docking Instrument with CMOS Image Sensor and All Radiation Resistant Lens Elements
(2020-08-01)
Lin, Sheng-Feng
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Chen, Cheng-Huan
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交大名義發表
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National Chiao Tung University
Built-in autonomous stereo vision devices play a critical role in the autonomous docking instruments of space vehicles. Traditional stereo cameras for space autonomous docking use charge-coupled device (CCD) image sensors, and it is difficult for the overall size to be reduced due to the size of the CCD. In addition, only the few outermost elements of the camera lens use radiation-resistant optical glass material. In this paper, a complementary metal-oxide semiconductor (CMOS) device is used as the image sensor, and radiation-resistant optical glass material is introduced to all lens elements in order to make a compact and highly reliable space grade instrument. Despite the limited available material, a fixed focus module with 7 lens elements and overall length of 42 mm has been achieved, while meeting all the required performance demands for the final vision-guided docking process.