Color‐tuning projection system for adaptive combination of high brightness and wide color gamut

Abstract— The demand for projectors with high brightness and wide color gamut has been increasing; however, UHP lamp projectors cannot deliver those two qualities efficiently and simultaneously because of its color‐separation system. The newly developed projection system — “Color‐Tuning Projection System” — realizes the adaptive combination of high brightness and wide color gamut with one projector. This projector features a fourth liquid‐crystal panel — “Color Tuner” — with a 3LCD optical engine, which controls yellow light separately from the RGB light of a UHP lamp. This color‐tuner‐based optical engine — “Color‐Tuning Optical Engine” — and a new color‐conversion signal‐processing algorithm — “Adaptive Color Conversion Algorithm” — controls the yellow‐light volume and corrects color‐shifted pixels according to the brightness and chromaticity analysis of the input image, key technologies of the Color‐Tuning Projection System. This additional panel system enables the projector to ach ieve up to 115% higher brightness and 120% wider color gamut according to the input image. This paper presents an innovative design concept, a novel technology regarding brightness and a color‐gamut conversion projection system, and the characteristics of the prototype.     

Laser display with single‐mirror MEMS scanner

Abstract— While arrayed DMD and LCD microdisplays are well‐established approaches for visualization tasks, image‐forming laser scanners are an emerging technology used to build miniaturized projection displays. A directly modulated RGB‐laser module consisting of diode lasers for red and blue and a frequency‐doubled semiconductor laser for green with color combining optics form the light source for the laser scanner have been developed. Subsequent beam‐shaping optics suppresses unwanted stray light and enables optimum illumination of the scanning mirror. The MEMS device features a single scanning mirror oscillating in two directions in resonant mode. This requires appropriate data delivery realized by a custom‐made driving logic, which converts the pixel stream originally arranged in rows and columns to the Lissajous‐like spot trajectory on the screen. Additionally, the increased image brightness at the vertical and horizontal borders of the field of view (FOV) is also compensated by the modulation of laser power. Theoretical investigations of the resulting maximum achievable system transmission are presented. Different systems, such as an extremely miniaturized monochrome projection head with an integrated diode laser and a full‐color projector have been realized. Important problems to be tackled are fast analog modulation of the laser power with high resolution and improved suppression of stray light and speckle.     

Multi‐viewer autostereoscopic display with dynamically addressable holographic backlight

Abstract— The Multi‐User 3‐D Television Display (MUTED), designed to provide three‐dimensional television (3‐D TV) by the display of autostereoscopic imagery to multiple viewers, each of whom should enjoy freedom of movement, is described. Such an autostereoscopic display system, which allows multiple viewers simultaneously by the use of head tracking, was previously demonstrated for TV applications in the ATTEST project. However, the requirement for a dynamically addressable, steerable backlight presented several problems for the illumination source. The MUTED system demonstrates significant advances in the realization of a multi‐user autostereoscopic display, partly due to the provision of a dynamic backlight employing a novel holographic laser projector. Such a technology provides significant advantages in terms of brightness, efficiency, laser speckle, and the ability to correct for optical aberrations compared to both imaging and scanned‐beam projection technologies.     

A YC‐separation‐type projector: High dynamic range with double modulation

Abstract— An experimental projector that features double modulation to obtain high‐resolution (4096 × 2160 pixels) and high‐dynamic‐range images has been developed. Although a conventional projector contains three modulators for red, green, and blue and outputs light after combining the modulated light from these three sources, our projector has an additional modulator for luminance that modulates the combined RGB modulated light. It can display high‐resolution color images by combining three low‐resolution panels for chrominance modulation and one high‐resolution panel for luminance modulation. In addition, the dynamic range is dramatically improved because the double‐modulation scheme minimizes black levels in projected images. The projector demonstrates an extremely high dynamic range of 1.1 million to 1 and 10‐bit tone reproduction.     

High‐pixel‐rate grating‐light‐valve laser projector

Abstract— A high‐pixel‐rate, high‐contrast (30,000:1) wide‐color‐gamut grating‐light‐valve laser projector is reported. A new optical engine enabling high‐frame‐rate (240 Hz) scan projection is employed. Panoramic wide‐angle‐scan projection with a 64:9 aspect ratio was also developed. Speckle noise is eliminated using a simple but highly efficient technique. The optical throughput efficiency of the grating‐light‐valve laser projector is reviewed.     

Refractive‐reflective optical system for realizing an ultra‐thin rear projector

Abstract— This paper presents a new optical system used in an ultra‐thin rear projector with a 1500‐mm diagonal size and 260‐mm depth. A refractive‐reflective optical system was developed to achieve a large projection angle of 136° with a small optical distortion of 0.1%. The optics consists of a convex aspherical mirror and a refractive lens. In addition, a new Fresnel screen composed of hybrid blades of refractive‐TIR (total internal reflection) elements was developed to attain good uniformity of brightness and color within the image area.     

MUTED: Multi‐user 3‐D display

Abstract— Research described in this paper encompasses the design and building of glasses‐free (autostereoscopic) displays that utilize a direct‐view liquid‐crystal display whose backlight is provided by a projector and novel steering optics. This is controlled by the output of a multi‐user head‐position tracker. As the displays employ spatial multiplexing on a liquid‐crystal‐display screen, they are inherently 2‐D/3‐D switchable with 2‐D being achieved by simply displaying the same image in the left and right channels. Two prototypes are described in this paper; one incorporating a holographic projector and the other a conventional LCOS projector. The LCOS projector version addresses the limitations of brightness, cross‐talk, banding in the images, and laser stability that occur in the holographic projector version. The future development is considered and a comparison between the prototypes and with other 3‐D displays is given.     

A 65‐in. slim (255‐mm depth) laser TV with wide‐angle projection optical system

Abstract— A high‐definition laser TV that employs a newly developed laser light source and a super‐wide‐angle projection optical system has been developed. This adoption of a laser light source with three primary colors helped to achieve an extremely wide color gamut, and, in addition, a compact optical engine, which has been optimized to the laser light source and contributed to the achievement of the stylish design of a large screen of 65 in., with the depth being only 255 mm.     

Multi‐primary image projector using programmable spectral light source

This paper presents a practical prototype of a multi‐primary image projector system in which light source spectra can be programmable for suiting any purpose. Our multi‐primary projection system is mainly configured with a light source component and an image projection component. The programmable light source can reproduce any spectral curve. Spatial images are then generated using a digital mirror device chip that quickly controls the intensity of the light source spectra in 2D image plane. The multi‐primary images in our projection system are reproduced by multiplexing the time‐sequential images with different primary colors. Our multi‐primary image projector realizes not only wide gamut projection but also spectral projection. To achieve this, we also show how light source spectra of four or six primary colors are designed.     

Projection‐based head‐tracking 3‐D displays

Abstract— This paper describes the construction and operation of four 3‐D displays in which each display produces two images for each eye and thus fits into the category of projection‐based binocular stereoscopic displays. The four 3‐D displays described are pico‐projector‐based, liquid‐ crystal—on—silicon (LCOS) conventional projector‐based, 120‐Hz digital‐light‐processor (DLP) projector‐ based, and the HELIUM3D system. In the first three displays, images are produced on a direct‐view LCD whose conventional backlight is replaced with a projection illumination source that is controlled by a multi‐user head tracker; novel steering optics direct the projector output to regions referred to as exit pupils located at the viewers' eyes. In the HELIUM3D display, the image information is supplied by a horizontally scanned, fast, light valve whose output is controlled by a spatial light modulator (SLM) to direct images to the appropriate viewers' eyes. The current statu s and the multimodal potential of the HELIUM3D display are described.     

Green laser sources optimized for highly efficient microdisplay‐based field‐sequential mobile projectors

Abstract— A novel green laser source, based on a monolithic cavity microchip laser platform, has been developed. The laser is designed to be a part of a miniature and efficient RGB light source for microdisplay‐based mobile projector devices. The use of highly efficient, periodically poled MgO‐doped lithium niobate as the non‐linear frequency doubler allows for a significant increase in the overall efficiency of the green microchip laser. Specifically, a 50–150‐mW green output with a wall‐plug efficiency exceeding 10% in the temperature range of greater than 40°C has been demonstrated. A compact package for this laser source with a volume less than 0.33 cm³ is discussed and results of performance tests are presented.     

World's first large size 77‐inch transparent flexible OLED display

Large flexible organic light‐emitting diode (OLED) display provides various electronic applications such as curved, bendable, rollable, and commercial display, because of its thinness, light weight, and design freedom. In this work, the process flow and key technologies to fabricate the world's first large size 77‐inch transparent flexible OLED display are introduced. “White OLED on TFT + color filter” method is used to fabricate the aforementioned display. On both thin‐film transistor and color filter substrates, transparent polyimide (PI) was used as plastic substrate with multi‐barrier. In case of a transparent flexible display, the multi‐barrier is required for the additional consideration to overcome the decrease of transmittance due to the difference in refractive index of the conventional multi‐barrier. We developed the special multi‐barrier to increase transparency with superior water vapor transition rate characteristic. The optimized amorphous indium gallium zinc oxide thin‐film transistors were employed on the multi‐barrier, and it shows the highly uniform electrical performance and reliability on plastic substrate. Also, the typical panel failure mechanism during laser lift‐off process caused by a particle in PI is studied, and a sacrificial layer was suggested between PI and a carrier glass to reduce the panel failure. Finally, we successfully realized the world's first 77‐inch transparent flexible OLED display with ultra‐high‐definition resolution, which can be rolled up to a radius of 80 mm with a transmittance of 40%.     

Eye‐safety analysis of current laser‐based LCOS projection systems

Abstract— A laser safety analysis for liquid‐crystal—on—silicon (LCOS) based imaging projection systems utilizing laser light sources is presented. It is shown that a typical laser‐based imaging projector is capable of providing a D65 white‐balanced luminous flux in excess of 20 lm while remaining Class 1 eye safe. By considering a Class 2 classification, it is shown that the same architecture is capable of providing several hundred lumens, a performance level which could potentially be applicable to a new class of high‐brightness miniature projection systems.     

An LCOS‐based digital‐cinema projector

Abstract— A digital cinema projector that utilizes three JVC QXGALCDs, and provides 12,000 lumens, 2000:1 contrast, and 3‐Mpixel resolution was developed. This system, which was described in a prior paper (see Ref. 10), has a novel optical configuration based on the use of intermediate imaging optics and wire‐grid polarizers and is described in greater detail in this paper. The polarization optics, including the polarization compensators, contribute to a system that provides high contrast at a low f/#, with a wide color gamut and minimal color shading at high power.     

New approaches to process simplification for large‐area high‐resolution TFT‐LCDs

Abstract— Novel process architectures are proposed for fabricating large‐area high‐resolution TFT‐LCDs with a minimal number of process steps. A low contact resistance between Al bus lines and the transparent conductive oxide layer, necessary for large‐area panels, is obtained by inducing a self‐formed inter‐metallic compound layer at the interface without using any additional buffer or capping layers. For enhanced brightness and resolution, a new TFT array structure integrated on a color‐filter substrate, referred to as an Array on Color Filter (AOC) structure, has been developed. Good‐quality TFTs were successfully constructed on the newly developed color filter for AOC within a sufficiently wide process margin. By adopting these novel technologies, a 15.0‐in. XGA prototype panel was fabricated and shows good display performance. Thus, these novel technologies have improved cost efficiency and productivity for TFT‐LCD manufacturing, and can be applied to the development of TFT‐LCDs of extended display area and enhanced resolution, benefiting from the low resistance bus lines, the high aperture ratio, and reduction in total process steps.     

Bistable FLCOS devices for doubled‐brightness micro‐projectors

Abstract— Optical output is of paramount importance to emerging ultra‐miniature projector products. Experimental bistable ferroelectric liquid‐crystal‐on‐silicon (FLCOS) projection microdisplay devices using newly developed FLC materials aligned on obliquely deposited SiO₂ have been developed. These devices enable the doubling of the illumination duty cycle, and hence doubling of the achievable projector light output, while maintaining a DC‐balanced electrical drive.     

Monocular hyper‐realistic AR head‐up display

We proposed and developed a novel monocular hyper‐realistic head dome projector for an amusement application and a novel monocular windshield augmented reality projector for augmented reality and head‐up display applications. They use monocular vision that eliminates the depth cues caused by binocular parallax information. Our developed monocular hyper‐realistic head dome projector and windshield augmented reality projector system achieved a high hyper‐reality performance with free depth perception and high visibility.     

Novel concept for full‐color electronic paper

Abstract— Despite a steep increase in commercial devices comprising paper‐like displays, a much desired feature is still missing: bright full‐color electronic paper. A new reflective‐display technology has been developed to solve this issue. For the first time, the principles behind this in‐plane electrophoretic technology will be presented, which enables the realization of full‐color reflective displays with a higher brightness than presently available e‐paper technologies, without compromising paper‐like properties such as viewing angle and ultra‐low power consumption. An additional major advantage (e.g., for future low‐cost manufacturing) is that, besides direct‐drive and active‐matrix configurations, a passive‐matrix option with analog gray levels has been successfully developed.     

Super‐short‐focus front projector with aspheric‐mirror projection optical system

Abstract— We have developed a new front projector with a super‐short projection distance of 0.65 m at 100 in. We installed a newly developed reflective‐type projection optical system in this projector, which was composed of only four aspheric mirrors that were free of color aberrations. Using this new system and a single‐chip DMD?, we projected a picture that had excellent sharpness and high contrast from 40 to 100 in. This paper describes the principles, design, and characteristics of the new WT600? front projector.     

Multi‐primary design of spectrally accurate displays

Abstract— Spectral color reproduction overcomes some inherent problems of colorimetric reproduction. An implementation of a spectral display for surface color reproduction, capable of reproducing a desired spectrum for each pixel, based on multi‐primary projection technology, is presented. A light source with a spectrum identical to that of the illumination is filtered by a positive linear combination of several color filters, which reproduces the reflectance spectra. The spectra of the color filters are tailored to span the space of possible surface spectra. Various methods for choosing the color filters vis‐à‐vis the required performance are discussed in detail. Soft‐proofing application is examined as a test case for the concept.