Browsing by Author "Ko, FJ"

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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.
High-efficiency micro-optical color filter for liquid-crystal projection system applications
(2000-03-01)
Ko, FJ
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
High-efficiency color filters composed of a microprism array, optical interference color filters, and a microlens array light compressor were developed to increase the optical throughput of liquid-crystal projection systems. The new devices utilize the energy of whole spectra by taking full advantage of a light compressor and interference dichroic filters to distribute the energy of spectra to the respective color pixel area. Thus high-efficiency micro-optical color filters allow efficient utilization of the energy of incident light and maximize the optical throughput of the projection system. (C) 2000 Optical Society of America.
Image Smoothing of liquid crystal display by a high-efficiency grating
(1999)
Chang, CW
;
Ko, FJ
;
Shieh, HPD
;
光電工程學系
;
Department of Photonics
The black matrix of Liquid Crystal Displays (LCDs) degrades image quality of projection system and Head Mount Displays (HMDs) by appearing as dark boundaries around each pixel. Therefore, an image smoothing technique is required to suppress these boundaries. With proposed image smoothing grating, not only the horizontal but also vertical parts of black matrix fade away into the first order diffraction beams. Moreover, the contrast of the smoothed image is close to the original value, because the second order beams can be designed to be negligible.
Improving the quality of liquid-crystal projection image by multilevel diffractive grating technique
(1999-07-01)
Ko, FJ
;
Wu, CK
;
King, HJ
;
Wu, SY
;
Shieh, HPD
A technique using multilevel diffractive gratings to suppress the discrete nature of liquid crystal display (LCD) projection images is demonstrated. The multilevel diffractive gratings, having a cross section similar to a staircase, are fabricated by VLSI processes and plastic molding. Upon positioning the diffractive gratings on the front surface of the LCD panel, the output light beams emitted from each pixel are diffracted mainly into the zeroth and the +/-first diffraction order light beams of equal energy. The light beams transformed by the diffractive gratings into orders higher than zeroth are able to fill up the dead space between each subpixel, and generate an array of images from each subpixel. As a result, the spatial frequency of the color subpixel distribution within the whole image is increased. Accordingly, the grain-like pixel structure in projection images is removed, at a slight expense of image resolution.
Multidirectional asymmetrical microlens array light control film for improved image in reflective color liquid crystal displays
(2002-02-01)
Huang, YP
;
Chen, JJ
;
Ko, FJ
;
Shieh, HPD
;
光電工程學系
A multidirectional asymmetrical microlens array light control film (MAMA-LCF) which can direct light incident from multiple directions collectively for viewing is demonstrated in achieving much enhanced brightness in reflective color super twisted-nematic liquid crystal displays (STN-LCDs). The MAMA-LCF, constructed with an asymmetrical microlens array and laminated onto the front surface of reflective color STN-LCDs, can yield a maximum gain of about 5 x the MgO standard white in a typical viewing region without visible dispersion, moire or parallax effects.
Multidirectional asymmetrical microlens-array light control plastic films for high performance reflective liquid crystal displays
(2002)
Shieh, HPD
;
Chiu, Y
;
Huang, YP
;
Ko, FJ
;
光電工程學系
Multidirectional asymmetrical microlens array light control films were developed to enhance image quality of reflective LCDs. Significant gain in both brightness and contrast ratio has been demonstrated without visible surface diffusion, Moire patterns and parallax.