The effects of glossy screens on the acceptance of flat‐panel displays

Abstract— The TCO requirements provide well‐known and recognized quality labels for displays. For these requirements to remain useful, they must continuously be reviewed and updated when necessary. The study described here was performed in response to the market trend of designing flat‐panel displays and notebooks with glare panels. The purpose of this study was to investigate subjective responses to display screens of different gloss levels for office workers working on different tasks under normal office‐lighting conditions. The study consisted of three parts, one where the users should set an acceptable reflex level, one where the user should rate their disturbance on a category scale, and one where the visual acuity of the users were investigated whether they were affected by glare or not. The results show that increasing gloss and increasing luminance levels had negative effects on the acceptance and the disturbance of reflexes. There were statistically significant differences in the acceptance and the disturbance levels between screens with low gloss and screens with high gloss, which suggests that screens with the highest gloss levels should be avoided. The study did not show an effect on the performance based on acuity testing.     

Organic‐polymer thin‐film transistors for active‐matrix flat‐panel displays?

Abstract— Organic‐polymer‐based thin‐film transistors (OP‐TFTs) look very promising for flexible, large‐area, and low‐cost organic electronics. In this paper, we describe devices based on spin‐coated organic polymer that reproducibly exhibit field‐effect mobility values around 5 × 10^?3 cm²/V‐sec. We also address fabrication, performance, and stability issues that are critical for the use of such devices in active‐matrix flat‐panel displays.     

Confined‐error‐diffusion algorithm for flat‐panel display

Abstract— The reduction of a structural pattern at specific gray levels caused by digital halftone methods is the subject of this paper. This problem is more severe in some flat‐panel displays because their black levels typically are brighter than other display blocks. A patented halftone algorithm, confined error diffusion (CED), that confines the error‐carry within the dither mask is described and extended. First, the CED algorithm that dynamically applies random error diffusion or the ordered‐dither method, depending upon image content, is described in detail. Finally, we propose an advanced CED algorithm for improving the gradation characteristics of the CED algorithm. The performance of the proposed algorithms is compared to the experimental results for natural test images. In order to verify the halftone quality, a structural similarity measure for color images by taking into account the interrelation between color channels is proposed, and the results based on the proposed method, the color similarity measure method, is given.     

Amorphous semiconductors for cold cathodes: A route to large‐area flat‐panel displays

Abstract— The field‐emission‐display (FED) technology examined in the early sixties used metal tips or Spindt cathodes in order to extract electron beams to excite phosphors. The tips were necessitated by the large work function the electrons needed to overcome in order to be released into the vacuum. In the early nineties it was noticed that “flat” diamond surfaces emitted electrons at relatively low electric fields. Just as its crystalline counterparts, amorphous‐carbon thin films also showed that this class of materials were also capable of electron emission at low threshold fields. By using flat emitters, technologist can remove a number of fabrication steps that otherwise would have been required to produce large‐area arrays of field emitters and therefore reduce the cost of production significantly. This paper will review the progress of the use of flat amorphous semiconductors as cold cathodes. New results that appear to point towards a space‐charge‐controlled emission mechanism as opposed to a purely surface emission process based upon Fowler‐Nordheim tunneling will be introduced, which have implications on the type of device structure that will ultimately be needed for electron field‐emission devices. Two possible cold‐cathode materials, namely, amorphous‐carbon and amorphous silicon, will be examined.     

Inorganic EL devices with high‐performance blue phosphor and application to 34‐in. flat‐panel televisions

Abstract— A high‐performance inorganic electroluminescence (EL) device has been successfully developed by using an EL structure with a thick dielectric layer (TDEL) and sputtered BaAl₂S₄:Eu blue phosphor. The luminance and efficacy were higher than 2300 cd/m² and 2.5 lm/W at L⁶⁰, 120 Hz, respectively. Furthermore, the luminance at L⁶⁰, 1.2 kHz was more than 23,000 cd/m². The phosphor layer has a single‐phase and a highly oriented crystalline structure. The phosphor also shows high stability in air. A 34‐in. high‐definition television (HDTV) has been developed by combining a TDEL structure and color‐conversion materials. The panels with an optimized color filter demonstrated a peak luminance of 350 cd/m², a color gamut of more than 100% NTSC, and a wide viewing angle similar to that of plasma‐display panels. The high reproducibility of the 34‐in. panels using our pilot line has been confirmed.     

Scintillator‐based flat‐panel x‐ray imaging detectors

Abstract— Large‐area amorphous‐silicon flat‐panel x‐ray imaging detectors were introduced commercially about 10 years ago and have seen a steady increase in both volume and number of applications since. The flat‐panel‐detector industry was made possible by manufacturing methods and equipment first developed for the display industry. Here, the different types of flat‐panel detectors are described, with focus on the scintillator‐based TFT/photodiode detector. The manufacturing process used for these detectors is explained and compared to that for displays. Detector operation is detailed, and the various medical and industrial applications are described. Finally, the performance metrics for these detectors and the impact of the performance requirements on detector design are discussed.     

A small‐area and low‐power data driver IC using two‐stage DAC with a capacitor array for active matrix flat‐panel displays

A small‐area and low‐power data driver integrated circuit (IC) using a two‐stage digital‐to‐analog converter (DAC) with a capacitor array is proposed for active matrix flat‐panel displays. The proposed data driver IC employs a capacitor array in the two‐stage DAC so as to reduce the DAC area and eliminate the need for a resistor string, which has high‐power consumption. To verify the proposed two‐stage DAC, a 20‐channel data driver IC with the proposed 10‐bit two‐stage DAC was fabricated using a 0.18‐μm complementary metal–oxide–semiconductor process with 1.8 and 6 V complementary metal–oxide–semiconductor devices. The proposed 10‐bit two‐stage DAC occupies only 43.8% of the area of a conventional 10‐bit two‐stage DAC. The measurement results show that the differential nonlinearity and integral nonlinearity are +0.58/?0.52 least significant bit and +0.62/?0.59 least significant bit, respectively. The measured interchannel deviation of the voltage outputs is 8.8 mV, and the measured power consumption of the 20‐channel data driver IC is reduced to 7.1 mW, which is less than half of the power consumed by the conventional one.     

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.     

Detrimental effects of O2 and CO2 on the cathode performance of flat‐matrix CRTs used for large‐scale flat displays

Abstract— The detrimental effects of O² and CO² on the cathode emissions of a flat‐matrix (FM) CRT and some methods which increase its life are described. Cathode emission gradually decreases over long‐term operation when an FM‐CRT is used as a tiling element in a large‐scale flat display. It is necessary that for the FM‐CRT the reduction of the emission current be within 10% in order to keep the operational life longer than 10,000 hours. The reason for the degradation of the cathode emission was clarified by experiments using high‐vacuum equipment. It was found from experiments that O² and CO², which are produced by the dissolution and activation of the oxide‐coated cathodes, are very harmful to emissions. It is, therefore, very important to lower the partial pressure of O² and CO² in the FM‐CRT in order to reduce their harmful influence on the oxide cathodes. Two methods were used to reduce their partial pressure in the FM‐CRT. One was to make the diameter of the evacuation tube larger and the other was to increase the quantity of the getters. It was found that the adoption of twice as many getters in the FM‐CRT was most useful in lowering the partial pressure of O² and CO². This has ensured that the life of an FM‐CRT is longer than 10,000 hours.     

Tetrahedrally bonded amorphous carbon for field‐emission displays

Abstract— Field emission from a series of tetrahedrally bonded amorphous‐carbon (ta‐C) films, deposited in a filtered cathodic vacuum arc, has been measured. The threshold field for emission and current densities achievable have been investigated as a function of sp³/sp² bonding ratio and nitrogen content. Typical as‐grown undoped ta‐C films have threshold fields of the order 10–15 V/μm and optimally nitrogen doped films exhibit fields as low as 5 V/μm. In order to gain further understanding of the mechanism of field emission, the films were also subjected to H₂, Ar, and O₂ plasma treatments and were also deposited onto substrates of different work function. The threshold field, emission current, and emission site densities were all significantly improved by the plasma treatment, but little dependence of these properties on work function of the substrate was observed. This suggests that the main barrier to emission in these films is at the front surface.     

Reduction of defects and improvement in the performance of blue phosphor for thick‐dielectric electroluminescent displays using Color‐by‐Blue

Abstract— Defect‐free large‐area inorganic thick‐dielectric EL (TDEL) displays using Color by Blue (CBB) technology have been successfully developed. We have achieved the world's highest blue‐phosphor luminance of 900 cd/m² for a single‐pixel device by using CBB and by optimizing the e‐beam gun configuration and the flow rate of H₂S in the vacuum chamber. By analyzing the defects on panels with triple‐pattern phosphors and CBB panels, we also found that the number of defects on CBB panels can be drastically reduced compared with those on triple‐pattern panels. The defect‐free 17‐in. VGA CBB panels show better characteristics, a high peak luminance of 600 cd/m² and a high contrast ratio of 1000:1, compared with those of triple‐pattern panels.     

Active‐matrix and flexible liquid‐crystal displays with carbon‐nanotube pixel electrodes

Abstract— The necessary processes to use random carbon‐nanotube networks as transparent conductors in twisted‐nematic liquid‐crystal displays have been developed, replacing indium tin oxide. Because the nanotubes are deposited vacuum‐free from suspension, the potential advantages are lower costs for material, equipment, and production. Nanotube networks are also much better suited for flexible displays than the commonly used metal oxides. With the developed processes, the world's first full‐color active‐matrix LCDs as well as directly addressed flexible displays on plastic substrates with carbon‐nanotube pixel electrodes, have been realized.     

Nano‐emissive display technology for large‐area HDTV

Abstract— Using nano‐emissive display (NED) technology, Motorola labs has successfully developed 5‐in. full‐color display prototypes. Carbon‐nanotube‐based field‐emission displays with a pixel size of 0.726 mm for a 42‐in. HDTV exhibit video image quality comparable to CRT displays and demonstrate a luminance of 350 cd/m². These novel low‐drive‐voltage NEDs take advantage of selective growth of CNTs to obtain the desired electron‐emission performance while maintaining inexpensive manufacturing due to a simple self‐focusing and self‐regulating planar structure. Improved video image quality and color purity are achieved with very low power consumption and without the need for an expensive focusing grid.     

Highly transparent and conductive CdO thin films as anodes for organic light‐emitting diodes: Film microstructure and morphology effects on performance

Abstract— Highly conductive and transparent CdO thin films have been grown on glass and on single‐crystal MgO(100) by MOCVD at 400°C and were used as transparent anodes for fabricating small‐molecule organic‐light emitting diodes (OLEDs). Device response and applications potential have been investigated and compared with those of control devices based on commercial ITO anodes. It is demonstrated that highly conductive CdO thin films of proper morphology can efficiently inject holes into such devices, rendering them promising anode materials for OLEDs. Importantly, this work also suggests the feasibility of employing other CdO‐based TCOs as anodes for high‐performance OLEDs.     

Advances towards high‐resolution pack‐and‐go displays: A survey

Abstract— Tiled displays provide high resolution and large scale simultaneously. Projectors can project on any available surface. Thus, it is possible to create a large high‐resolution display by simply tiling multiple projectors on any available regular surface. The tremendous advancement in projection technology has made projectors portable and affordable. One can envision displays made of multiple such projectors that can be packed in one's car trunk, carried from one location to another, deployed at each location easily to create a seamless high‐resolution display, and, finally, dismantled in minutes to be taken to the next location — essentially a pack‐and‐go display. Several challenges must be overcome in order to realize such pack‐and‐go displays. These include allowing for imperfect uncalibrated devices, uneven non‐diffused display surfaces, and a layman user via complete automation in deployment that requires no user invention. We described the advances we have made in addressing these challenges for the most common case of planar display surfaces. First, we present a technique to allow imperfect projectors. Next, we present a technique to allow a photometrically uncalibrated camera. Finally, we present a novel distributed architecture that renders critical display capabilities such as self‐calibration, scalability, and reconfigurability without any user intervention. These advances are important milestones towards the development of easy‐to‐use multi‐projector displays that can be deployed anywhere and by anyone.     

Comparison of reflective PNLCDs and reflective single‐polarizer Heilmeier guest‐host displays

In this paper, the applicability of a zero‐polarizer reflective display (PNLC) and a single‐polarizer reflective display (Heilmeier guest host) for direct‐view applications is analyzed. A measurement set‐up is designed to analyze the applicability of all types of reflective displays. Simulation of the different types of illumination caused by the environmental light is essential for this set‐up. The measurements indicate that the contrast ratio and reflectance greatly depend on the type of illumination. It is demonstrated that the worst‐case illumination for one display technology may be the best‐case illumination for another one and vice versa.     

A course on thin‐film transistor circuit design for modern displays

A new subject‐specific course on thin‐film transistor (TFT) circuit design is introduced, covering related knowledge of display technologies, TFT device physics, processing, characterization, modeling and circuit design. A design project is required for students to deepen the understanding even more and get hands‐on design experience. This course can be an intense 1‐week course to offer a full training of design engineers in an organized way to meet the ever‐increasing needs in display industry for TFT circuit design specialists. It can also be organized in one semester for electrical engineering Master's and Ph.D. students.     

Substrate‐free cholesteric liquid‐crystal displays

Abstract— This paper demonstrates the first substrate‐free cholesteric liquid‐crystal displays. The encapsulated cholesteric displays are ultra‐thin (with a total thickness around 20 μm) and ultra‐lightweight (0.002 g/cm²). The displays exhibit unprecedented conformability, flexibility, and drapability while maintaining electro‐optical performance and mechanical integrity. All functional display layers are sequentially coated on a preparation substrate and then lifted‐off from the preparation substrate to form a free‐standing display. The display fabrication process, electro‐optical performance, and display flexibility are discussed.     

Comb‐on‐plane switching electrodes for liquid‐crystal displays

Abstract— Although the common twisted‐nematic liquid‐crystal displays (TN‐LCD) has excellent contrast and low color dispersion, it suffers from small viewing angle when driven into the homeotropic state. Among the many techniques proposed, in‐plane switching (IPS) has been quite effective in improving viewing angle. However, there may be difficulty in adopting conventional IPS to higher‐definition displays because it suffers from limited storage capacitance and reduced transmittance. A new comb‐on‐plane switching (COPS) electrode design is proposed. Compared to conventional IPS, COPS allows for lower switching voltage and offers advantages including naturally scalable storage capacitance, wide viewing angle with TN‐like high transmittance, and low color dispersion.     

Oil thermal annealed nano‐structured indium tin oxide thin films for display applications

Indium tin oxide‐coated thin films (200 nm) are deposited on glass substrates by using R.f. sputtering technique. Here, we investigate the influence of new technique of treatment, which is called as “oil thermal annealing” on the nano‐structured indium tin oxide thin films at fixed temperature (150 °C) which improves adhesion strength, electrical conductivity and optical properties (transmittance) of the films. Oil thermal annealing is used to reduce inherent defects that may be introduced during the prepared thin film and cooling processes. Proposed technique is highly suitable for liquid crystal displays, solar cells and organic light emitting diodes, and many other display‐related applications.