g-Huan Chen

Patterned structure of remote phosphor for phosphor-converted white LEDs.

High efficiency white light-emitting diodes with superior color-mixing have been investigated. It is suggested that the patterned remote phosphor structure could improve the uniformity of angular-dependent correlated color temperature (CCT) and achieve high chromatic stability in wider operating current range, as compared to the conventional remote phosphor coating structure. In this experiment, we employed a pulse spray coating method to place the patterned phosphor on the package and to leave a window region. The window area, a clear space without coating of the phosphor not only increases the extraction efficiency of blue rays at large angle, but also improves the stability of angular-dependent CCT. Moreover, the CCT deviation could be reduced from 1320 K to 266 K by this patterned remote phosphor method, and the stray blue/yellow light within the package can be effectively reduced and controlled. The design was verified both experimentally and theoretically.

Liquid crystal panel for high efficiency barrier type autostereoscopic three-dimensional displays

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.

32.3: Laser-Illuminated Three-Panel LCoS Projector with a Vibrating Diffractive Microlens-Array Beam Shaper

A RGB lasers illuminated three-panel LCoS projector has been developed to demonstrate the viability of a double-side microlens array as a diffractive beam shaper. By oscillating the beam shaper, both the uniformity and speckle pattern were significantly improved. The contrast ratio of the image speckle was measured to be below 8%.

Sub-15 nm linewidth gratings using roll-to-roll nanoimprinting and plasma trimming to fabricate flexible wire-grid polarizers with low colour shift

Sub-15 nm-wide gratings with a high aspect ratio of up to 16:1 were fabricated using roll-to-roll nanoimprinting and plasma trimming to achieve high optical performance (up to 12 000:1 extinction ratio with an average transmittance of 82%) and low colour shift (transmittance variation less than 3%) flexible wire-grid polarizers for display applications. We applied two imprint platforms onto glass and plastic substrates to identify the optical properties and characteristics of each fabrication process. To enhance the tolerance, reproducibility, and optical performance of the process, the grating profile symmetry and varying residual layer thicknesses were precisely simulated and controlled to achieve the design targets.

Color separation system with angularly positioned light source module for pixelized backlighting

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.

Low speckle laser illuminated projection system with a vibrating diffractive beam shaper

Currently the major issues in applying the laser as an illumination source for projectors are beam shaping and laser speckle. We present a compact total solution for both issues by using a diffractive beam shaper associated with a cylindrical lens for the illumination optics and a vibrating motor attached to the beam shaper to eliminate speckle on the projection screen. The diffractive beam shaper features a double-sided microlens array with a lateral shift to each other. The illumination pattern is free of zero diffraction order mainly due to the continuous and spherical surface relief of the lenslet, which can be accurately fabricated with diamond turning and injection molding without quantizing surface relief, so that the illumination pattern on the microdisplay can match the design very well with high diffraction efficiency. In addition, the vibration of the diffractive beam shaper in the longitudinal mode has been found effective for eliminating the dot pattern in the illumination and reducing laser speckle on the projection screen. The proposed laser illuminator has been implemented on a three-panel LCoS projector engine to replace the traditional UHP lamp. The uniformity and speckle contrast are measured to be 78% and 5.5% respectively, which demonstrates the feasibility and potential of the proposed scheme.

Polarized backlight with constrained angular divergence for enhancement of light extraction efficiency from wire grid polarizer.

Efficiency of liquid crystal displays highly depends on the amount of polarized light emerging from the backlight module. In this paper, a backlight architecture using a nanoimprint wire grid polarizer for polarization recycling is proposed and studied, in which the extraction efficiency of polarized light is the major concern. The backlight module is composed of the stack of a wire grid polarizer, a lenticular array and a light guide plate. The light guide plate features interleaving v-groove and trapezoidal ridge coated with aluminum on the top surface, and scattering dot array on the bottom. The angular divergence of emerging light from the light guide plate can be well constrained so as to exploit the angular range with the best transmission of polarized light for the wire grid polarizer. The prototype of a 2.5-inch module has demonstrated an angular divergence of 48°. The overall extraction efficiency of polarized light enhanced by 21% and uniformity of 76% have been achieved.

50.4: High Resolution Autostereoscopic 3D Display with Proximity Projector Array

A 3D architecture which exploits proximity projector array to project tiled image of low magnification ratio from microdisplays has been proposed as a solution for large screen and high resolution spatial multiplex autostereoscopic display. with descent lenticular and projection optics design associated with dedicated pixel mask, the proposed 3D configuration shows low crosstalk between viewing zones and demonstrates a potential alternative to increase pixel count for wide view and high resolution 3D displays.

Optical simulation for cross‐talk evaluation and improvement of autostereoscopic 3‐D displays with a projector array

— Multi-view spatial-multiplexed autostereoscopic 3-D displays normally use a 2-D image source and divide the pixels to generate perspective images. Due to the reduction in the resolution of each perspective image for a large view number, a super-high-resolution 2-D image source is required to achieve 3-D image quality close to the standard of natural vision. This paper proposes an approach by tiling multiple projection images with a low magnification ratio from a microdisplay to resolve the resolution issue. Placing a lenticular array in front of the tiled projection image can lead to an autostereoscopic display. Image distortion and cross-talk issues resulting from the projection lens and pixel structure of the microdisplay have been addressed with proper selection of the active pixel and adequate pixel grouping and masking. Optical simulation has shown that a 37-in. 12-view autostereoscopic display with a full-HD (1920 × 1080) resolution can be achieved with the proposed 3-D architecture.

P-202: High Transmittance LC Pixel Design for Multi-View 3D Mobile Display

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 ∼9 ° to ∼30 ° compared with conventional multi-domain VA.