Patterned liquid‐crystal laser film for multi‐dimensional multi‐color emissive film technology

Abstract— A two‐dimensional array consisting of dye‐doped reflection‐mode holographic‐polymer‐dispersed liquid crystal (H‐PDLC) lasers with alternating pitch lengths is presented. These post structures each reflect at a narrow bandwidth of light. The addition of laser dye to the H‐PDLC system allows for the generation of laser emission at the edge of the reflection band, or photonic band gap. In patterning these H‐PDLC post structures, a narrow‐linewidth patterned emissive color film is realized. The potential of such films and their implication in the display industry is discussed. In creating a three‐color array, an active emissive color film could replace the backlight and color filter components within the display. Such a patterned system would possess a wide color gamut, through spatial color synthesis, formed by narrow‐linewidth lasing structures with well‐defined wavelengths of emission.     

A multi‐plane optical see‐through head mounted display design for augmented reality applications

Augmented reality (AR) display technology greatly enhances users' perception of and interaction with the real world by superimposing a computer‐generated virtual scene on the real physical world. The main problem of the state‐of‐the‐art 3D AR head‐mounted displays (HMDs) is the accommodation‐vergence conflict because the 2D images displayed by flat panel devices are at a fixed distance from the eyes. In this paper, we present a design for an optical see‐through HMD utilizing multi‐plane display technology for AR applications. This approach manages to provide correct depth information and solves the accommodation‐vergence conflict problem. In our system, a projector projects slices of a 3D scene onto a stack of polymer‐stabilized liquid crystal scattering shutters in time sequence to reconstruct the 3D scene. The polymer‐stabilized liquid crystal shutters have sub‐millisecond switching time that enables sufficient number of shutters to achieve high depth resolution. A proof‐of‐concept two‐plane optical see‐through HMD prototype is demonstrated. Our design can be made lightweight, compact, with high resolution, and large depth range from near the eye to infinity and thus holds great potential for fatigue‐free AR HMDs.     

Electric‐field‐driven LC lens for 3‐D/2‐D autostereoscopic display

Abstract— The use of an electric‐field‐driven liquid‐crystal (ELC) lens cell for switching between a 3‐D and 2‐D display is proposed. Due to the phase retardation of the non‐uniform LC directors, an ELC lens functions the same as a geometric lens. The parameters of an ELC for 3‐D applications are optimized through the simulation of the electrode configuration and voltage levels. A prototype was made where the ELC lens is placed in front of a liquid‐crystal display (LCD) 15 in. on the diagonal with a 99‐μm subpixel pitch. Under zero voltage, the ELC lens is a transparent medium and the users can see a clear 2‐D image. In 3‐D mode, the ELC lens array performs the same as a cylindrical lens array to the incident vertical polarization under suitable driving voltages. Placing a half‐wave plate between the LCD and ELC lens is proposed to change the polarization of the LCD to be parallel with the polarization lens direction of the ELC lens. The measurement of the horizontal luminance profile, performance of the ELC lens, and feasibility for 3‐D/2‐D switching was verified. The fabrication process for the ELC lens is compatible with the current LCD production process and enables the accurate control of the lens pitch of the ELC lens.     

Practical implementation of a depth‐feeling‐enhanced two‐plane electro‐floating display system using three‐dimensional integral images

Abstract— Although there are numerous types of floating‐image display systems which can project three‐dimensional (3‐D) images into real space through a convex lens or a concave mirror, most of them provide only one image plane in space to the observer; therefore, they lack an in‐depth feeling. In order to enhance a real 3‐D feeling of floating images, a multi‐plane floating display is required. In this paper, a novel two‐plane electro‐floating display system using 3‐D integral images is proposed. One plane for the object image is provided by an electro‐floating display system, and the other plane for the background image is provided with the 3‐D integral imaging system. Consequently, the proposed two‐plane electro‐floating display system, having a 3‐D background, can provide floated images in front of background integral images resulting in a different perspective to the observer. To show the usefulness of the proposed system, experiments were carried out and their results are presented. In addition, the prototype was practically implemented and successfully tested.     

2‐D/3‐D displays based on switchable lenticulars

Abstract— An attractive concept for 3‐D displays is the one based on LCDs equipped with lenticular lenses. This enables autostereoscopic multiview 3‐D displays without a loss in brightness. A general issue in multiview 3‐D displays is their relatively low spatial resolution because the pixels are divided among the different views. To overcome this problem, we have developed switchable displays, using liquid‐crystal (LC) filled switchable lenticulars. In this way, it is possible to have a high‐brightness 3‐D display capable of fully exploiting the native 2‐D resolution of the underlying LCD. The feasibility of LC‐filled switchable lenticulars was shown in several applications. For applications in which it is advantageous to be able to display 3‐D and 2‐D content simultaneously, a 42‐in. locally switchable prototype having a matrix electrode structure was developed. These displays were realized using cylindrically shaped lenticular lenses in contact with LC. An alternative for these are lenticulars based on gradient‐index (GRIN) LC lenses. Preliminary results for such switchable GRIN lenses are presented as well.     

Multi‐view 3‐D display employing a flat‐panel display with slanted pixel arrangement

Abstract— A flat‐panel display with a slanted subpixel arrangement has been developed for a multi‐view three‐dimensional (3‐D) display. A set of 3M × N subpixels (M × N subpixels for each R, G, and B color) corresponds to one of the cylindrical lenses, which constitutes a lenticular lens, to construct each 3‐D pixel of a multi‐view display that offers M × N views. Subpixels of the same color in each 3‐D pixel have different horizontal positions, and the R, G, and B subpixels are repeated in the horizontal direction. In addition, the ray‐emitting areas of the subpixels within a 3‐D pixel are continuous in the horizontal direction for each color. One of the vertical edges of each subpixel has the same horizontal position as the opposite vertical edge of another subpixel of the same color. Cross‐talk among viewing zones is theoretically zero. This structure is suitable for providing a large number of views. A liquid‐crystal panel having this slanted subpixel arrangement was fabricated to construct a mobile 3‐D display with 16 views and a 3‐D resolution of 256 × 192. A 3‐D pixel is comprised of 12 × 4 subpixels (M = 4 and N = 4). The screen size was 2.57 in.     

Performance of liquid‐crystal displays for fire‐service thermal‐imaging cameras

Abstract— As use of handheld thermal‐imaging cameras (TICs) becomes more prevalent in the first‐responder community, it is important that standard test metrics be available to characterize imaging performance. A key performance consideration is the quality of the image presented on the TIC display. This paper focuses on TICs that use liquid‐crystal displays to render an image for the user. Current research on TIC performance for first‐responder applications makes use of trained observers and/or composite‐video‐output‐signal measurements. Trained observer tests are subjective and composite video output tests do not evaluate the performance of the complete imaging system. A non‐destructive objective method was developed that tests the performance of the entire thermal‐imaging system, from the infrared sensor to the display. A thermal target was used to correlate the measured thermal imager composite video output signal with the luminance of the display. A well‐characterized charge‐coupled‐device (CCD) camera and digital recording device were used to measure the display luminance. An electro‐optical transfer function was determined that directly relates the composite video output signal to the luminance of the display, providing a realistic characterization of system performance.     

Transflective blue‐phase liquid‐crystal display with corrugated electrode structure

Abstract— A transflective polymer‐stabilized blue‐phase liquid‐crystal display (BP‐LCD) with a corrugated electrode structure is proposed. To balance the optical phase retardation between the transmissive (T) and reflective (R) regions, two device structures are proposed. The first device structure has the same inclination angles but different cell gaps in the T and R regions. And the second device structure has the same cell gap but different inclination angles in the T and R regions. Both of the device structures can obtain well‐matched VT and VR curves. This display exhibits low operating voltage, high optical efficiency, and a wide viewing angle.     

Design conditions for attractive reality in mobile‐type 3‐D display

Abstract— An autostereoscopic 3‐D display suitable for the mobile environment is prototyped and evaluated. First, the required conditions for a 3‐D display in a mobile environment are considered, and the three major requirements are clarified: small size, viewing‐position flexibility, and application support. An application of a mobile‐type 3‐D display should be different from that of a large‐sized 3‐D display because a mobile‐type 3‐D display cannot realize the feeling of immersion while large‐sized 3‐D displays can realize it easily. From this assumption, it is considered that it is important to realize the feeling to handle a 3‐D image. Three types of 3‐D displays are developed to satisfy these requirements. They are subjectively evaluated to confirm their attractiveness. Results of the tests show that intuitive interaction can increase the reality of the 3‐D image in the sense of unity and also can improve the solidity and depth impression of the 3‐D image.     

Multi‐primary‐color LCD: Its characteristics and extended applications

Abstract— The development of multi‐primary‐color (MPC) display systems is one of the big paradigm shifts in recent display technologies and induces new potentials of display devices. The development of MPC display systems for different goals is briefly reviewed. Especially, by employing MPC systems, it is possible to reproduce the real material colors faithfully and efficiently. For signal processing, MPC systems have a big advantage in the so‐called color‐reproduction redundancy. A number of applications can be derived from this characteristic, such as improving the viewing‐angle dependency issue and power savings. On the other hand, MPC systems have a typical trade‐off versus RGB‐standardized input signals, especially for reproducing bright green. New algorithms to moderate this trade‐off on MPC systems by employing color‐reproduction redundancy are proposed. The goal of our algorithms is to maintain the compatibility with RGB‐based input signals though the initial display design so that the characteristics of MPC systems are not changed or lost. These algorithms indicate that MPC display systems are applicable not only for a specifically limited objective but also for other applications, e.g., TV broadcasting.     

Large‐area black/white bistable cholesteric liquid‐crystal display and the thermal‐addressing system

Abstract— A 3‐m‐length black/white bistable cholesteric liquid‐crystal display was made by a roll‐to‐roll process and the display area is 25 × 300 cm. The black/white performance was made by black nano‐pigment and blended ChLC droplets with different wavelengths. It was written by a thermal‐addressing system, realizing high resolution and low cost.     

A single‐substrate multicolor cholesteric liquid‐crystal display prepared through ink‐jet printing

Abstract— Ink‐jet printing was used to prepare a single‐substrate multicolor cholesteric liquid‐crystal (Ch‐LC) display incorporating three Ch‐LCs exhibiting different reflective wavelengths. A room‐temperature low‐vacuum chemical‐vapor‐deposition process was developed for coating a thin polymer film onto the Ch‐LC so that the top electrode could be coated onto the Ch‐LC layer. Herein, the successful operation of such a 10.4‐in. QVGA Ch‐LC display at 40 V will be described.     

2‐D/3‐D switchable displays

Abstract— In this paper, the design of a lenticular‐based 2‐D/3‐D display for mobile applications is described. This display combines look‐around capability with good 3‐D resolution. In order to allow high‐resolution datagraphic applications, a concept based on actively switched lenses has been developed. A very noticeable problem for such displays is the occurrence of dark bands. Despite slanting the lenticular and defocusing the lens, banding becomes unacceptable when the display is viewed from an angle. As a solution, fractional viewing systems to reduce the banding intensity by almost two orders of magnitude is introduced. The resulting 3‐D display can be viewed from any horizontal direction without banding.     

Analysis and reduction of dark zone in ultra‐thin wedge‐plate displays

Abstract— A wedge plate can be used as the screen of a display, and the thickness of the display can be incredibly thin. In this paper, a basic formula for ray tracing in such a wedge plate is deduced. The fundamental limitation on the display quality of a wedge plate is explored, and the formation of a dark zone on the display screen is analyzed and verified numerically. Experimental exploration and confirmation of one 14‐in. acrylic wedge plate with a white‐light‐emitting diode is also provided. Two approaches to eliminate the dark zone are proposed, and the corresponding numerical demonstration of a 52‐in. wedge‐plate display is also shown.     

Nanoparticle‐embedded polymer‐dispersed liquid crystal for paper‐like displays

Abstract— A polymer‐dispersed liquid‐crystal (PDLC) matrix template embedded with nano/microparticles can be backfilled/infiltrated with a dye‐doped liquid crystal for a paper‐like reflective display. In this way, a desirable degree of diffusion can be realized to reduce the viewing‐angle dependency of a gain reflector and metallic glare without changing other electro‐optical properties.     

Static‐volumetric display using rotational‐slicing approach for rendering 3‐D images

Abstract— This work is related to static volumetric crystals which scintillate light when two laser beams are intersected within the crystal. The geometry in this crystal is optimized for linear slices. Most volumetric displays are based on rotational surfaces, which generate the images, while the projected images are sliced in a rotational sweep mode. To date, the majority of 3‐D graphic engines based on static‐volume displays have not been fully developed. To use an advanced 3‐D graphic engine designed for a swept‐volume display (SVD) with a static‐volume display, the display must emulate the operation of a SVD based on a rotational‐slicing approach. The CSpace® 3‐D display has the capability to render 3‐D images using the rotational‐slicing approach. This paper presents the development of a rotational‐slicing approach designed to emulate the operation of a SVD within the image volume of a static‐volume display. The display software has been modified to divide the 3‐D image into 46 slices, each passing through the image center and rotated at a fixed angle from the previous slice. Reconstructed 3‐D images were demonstrated using a rotational‐slicing approach. Suggestions are provided for future implementations that could aid in the elimination of elongations and distortions, which occur within specified slices.     

A controller design for micro‐cup active‐matrix electrophoretic displays

Abstract— The active‐matrix electrophoretic display (AMEPD) has been commonly used for the applications of smart handheld reading devices such as e‐books and e‐newspapers. This paper presents a controller IC design for the AMEPD backend system which reduces the total hardware cost compared to that of the conventional design. By contrast, this study also provides a driving method for image displays. The prototyped controller is connected to a 6‐in. AMEPD panel, and good display quality has demonstrated the effectiveness of the proposed controller design.     

Psychophysical evaluations of a current multi‐view 3‐D display: Its advantages in glossiness reproduction

Abstract— Although two‐view 3‐D displays requiring stereo glasses are on the market, the shape of objects they present is distorted when the observer's head moves. This problem can be solved by using a (passive) multi‐view 3‐D display because such a display can produce motion parallax. Another problem has to do with the surface quality of the presented object, but little is known about the fidelity of such displays as far as the surface quality goes. Previously, it was found that a two‐view 3‐D display has a problem in which glossiness deteriorates when the observer's head moves and that it can be alleviated by using a head tracker, whose data enables the display to produce correct motion parallax and luminance changes when the viewer's head moves. Here, it was determined whether this problem can be solved by using commercially available multi‐view 3‐D displays, whose finite number of viewpoints and certain amount of cross‐talk, however, make luminance changes inexact and smaller than they should be. It was found that this display can solve the problem to a certain extent.     

Color displays and flexible displays using quick‐response liquid‐powder technology for electronic paper

Abstract— Color displays and flexible displays that use electronic liquid powder have been developed. Novel types of color displays using either a colored powder or a color filter are discussed. We have also developed a flexible display with low‐cost substrate films with a high‐throughput roll‐to‐roll manufacturing method. These technologies enable a QR‐LPD to be widely used as an electronic‐paper display.     

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%.