Chun-Ho Chen

Broadband and omnidirectional antireflection employing disordered GaN nanopillars

Disordered GaN nanopillars of three different heights: 300, 550, and 720 nm are fabricated, and demonstrate broad angular and spectral antireflective characteristics, up to an incident angle of 60? and for the wavelength range of lambda=300-1800 nm. An algorithm based on a rigorous coupled-wave analysis (RCWA) method is developed to investigate the correlations between the reflective characteristics and the structural properties of the nanopillars. The broadband and omnidirectional antireflection arises mainly from the refractive-index gradient provided by nanopillars. Calculations show excellent agreement with the measured reflectivities for both s- and p- polarizations.

A Field Sequential Color LCD Based on Color Fields Arrangement for Color Breakup and Flicker Reduction

The field sequential color (FSC) mechanism can effectively generate multi-primary color fields in temporal sequence to form a full-color image. Color breakup (CBU), however, has appeared intrinsically in conventional FSC displays to degrade visual qualities. A novel CBU suppression method, color fields arrangement (CFA), was proposed to eliminate the artifacts for FSC liquid crystal displays (LCDs). The modified order of consecutive color fields results in superimposed color images on a retina without CBU. Additionally, the 4-CFA method with a field rate of 240 Hz was found to avoid the flicker phenomenon on static images. The proposed method was successfully implemented on a 5.6-in optically compensated bend (OCB) LC panel. Our results confirm that the visibility of CBU artifacts can be reduced as the evaluation of dynamic and static models.

3-D Mobile Display Based on MoirÉ-Free Dual Directional Backlight and Driving Scheme for Image Crosstalk Reduction

A novel micro-grooved structure of lightguides and a sequential driving scheme of light sources were demonstrated in achieving comparable image qualities of 3-D displays to that of 2-D displays. The modified distribution of micro-grooves not only locates viewing cones for respective eyes but also suppresses the moire pattern, which might occur when a periodic micro-grooved structure and a color filter are superimposed. The configuration of lightguides for a 1.8-in liquid crystal display (LCD) panel can yield acceptable 3-D perceptions at the viewing distance of 7-23 cm and the brightness uniformity of greater than 83%. In addition, the driving scheme of light sources in synchronization with parallax images can project images to the viewers respective eyes sequentially. With the refreshing sub-frame rate of 190 Hz and double displaying parallax images, the image crosstalk of 3-D perceptions can be efficiently reduced for an LC response time of 7.0 ms.

Adaptive LC/BL Feedback Control in Field Sequential Color LCD Technique for Color Breakup Minimization

A full-color image on field sequential color (FSC) displays is composed of color fields in temporal sequence. With the FSC mechanism, color filters of liquid crystal displays (LCDs) can be removed to heighten the light efficiency and lower the material cost. Color breakup (CBU), however, has appeared intrinsically to degrade visual qualities. A novel gray level determination of liquid crystal and backlight (LC/BL) was proposed to suppress the CBU artifact on FSC-LCDs. Based on the image content in each frame, a dominated color-mixed field was found to minimize the color difference between the CBU and original image. Additionally, the feedback algorithm for the adaptive LC/BL signals was developed and implemented on a 32-inch optically compensated bend (OCB) mode LC panel. According to the evaluation of experiments and observations, the proposed method has been demonstrated to greatly suppress CBU in LCD applications.

Localized Joule Heating As a Mask-Free Technique for the Local Synthesis of ZnO Nanowires on Silicon Nanodevices

We report a mask-free technique for the local synthesis of ZnO nanowires (NWs) on polysilicon nanobelts and polysilicon NW devices. First, we used localized joule heating to generate a poly(methyl methacrylate) (PMMA) nanotemplate, allowing the rapid and self-aligned ablation of PMMA within a short period of time (ca. 5 μs). Next, we used ion-beam sputtering to prepare an ultrathin Au film and a ZnO seed layer; a subsequent lift-off process left the seed layers selectively within the PMMA nanotemplate. Gold nanoparticles and ZnO NWs were formed selectively in the localized joule heating region.

Effects of Backlight Profiles on Perceived Image Quality for High Dynamic Range LCDs

Locally dimmable backlight modules can effectively improve the dynamic range of liquid-crystal displays (LCDs) to human vision range. The resolution of addressable segments and the optical profile of these segments primarily determine the perceived image quality such as the contrast enhancement and boundary visibility. Contrast sensitivity function, the gradient of backlight image of of background luminance (units: nits/degree), was found as the threshold for the visibility of boundaries. Additionally, a study on a recommended profile with an economical number of segments was studied. Our results confirm that image qualities with this backlight modulation are improved in contrast enhancement and boundary perception using 2D-dimming backlight.

P-72: Inclined LED Array for Large-Sized Backlight System

Inclined LED array and flat bottom reflector for large-sized backlight system was proposed to obtain high brightness uniformity. Tilted LEDs rearrange the angular distribution of light source optimized without extra designing optical configuration. The novel backlight system is simpler in structure than the traditional ones. Optimum inclined angle of 10 degrees of LEDs on 22″ panel as designed example yields the competitive uniformity of 85% and a color gamut of a factor of 1.3 wider than those of commercial CCFL backlight.

Using silicon nanowire devices to detect adenosine triphosphate liberated from electrically stimulated HeLa cells

In this study, we used a biosensor chip featuring Abl tyrosine kinase-modified silicon nanowire field-effect transistors (SiNW-FETs) to detect adenosine triphosphate (ATP) liberated from HeLa cells that had been electrically stimulated. Cells that are cultured in high-ionic-strength media or buffer environments usually undermine the sensitivity and selectively of SiNW-FET-based sensors. Therefore, we first examined the performance of the biosensor chip incorporating the SiNW-FETs in both low- and high-ionic-strength buffer solutions. Next, we stimulated, using a sinusoidal wave (1.0 V, 50 Hz, 10 min), HeLa cells that had been cultured on a cell-culture chip featuring interdigitated electrodes. The extracellular ATP concentration increased by ca. 18.4-fold after electrical stimulation. Finally, we detected the presence of extracellular ATP after removing a small amount of buffer solution from the cell-cultured chip and introducing it into the biosensor chip.

66.4: Spatial‐temporal Division in Field Sequential Color Technique for Color Filterless LCD

For color filterless display, a novel spatial and temporal division (STD) field sequence color (FSC) display technique divides each frame into many temporary sub-frames for improving color breakup (CBU) and motion blur effects. Fast refresh frequencies enhance the image quality. Spatial and temporal division achieves low cost and power consumption. Keywords: field sequential color, liquid crystal display, color breakup, color filterless, Motion Blur, LED Backlight.For color filterless display, a novel spatial and temporal division (STD) field sequence color (FSC) display technique divides each frame into many temporary sub-frames for improving color breakup (CBU) and motion blur effects. Fast refresh frequencies enhance the image quality. Spatial and temporal division achieves low cost and power consumption. Keywords: field sequential color, liquid crystal display, color breakup, color filterless, Motion Blur, LED Backlight.

Long working range light field microscope with fast scanning multifocal liquid crystal microlens array

The light field microscope has the potential of recording the 3D information of biological specimens in real time with a conventional light source. To further extend the depth of field to broaden its applications, in this paper, we proposed a multifocal high-resistance liquid crystal microlens array instead of the fixed microlens array. The developed multifocal liquid crystal microlens array can provide high quality point spread function in multiple focal lengths. By adjusting the focal length of the liquid crystal microlens array sequentially, the total working range of the light field microscope can be much extended. Furthermore, in our proposed system, the intermediate image was placed in the virtual image space of the microlens array, where the condition of the lenslets numerical aperture was considerably smaller. Consequently, a thin-cell-gap liquid crystal microlens array with fast response time can be implemented for time-multiplexed scanning.