Liquid Crystal Display TV Research Articles

FPC Design Guidelines for Enabling High-Speed Intrapanel Interface in Large-Size LCD TVs

In this work, we propose flexible printed circuit (FPC) design guidelines for high-speed signal implementation in large-size and high-resolution liquid crystal display (LCD) TV modules by analyzing signal integrity (SI) characteristics through simulation and measurement. We observed that designing an FPC for LCD TV modules that can minimize insertion loss and crosstalk in the channel is critical to successfully implementing multi-Gbps signal characteristics in large-size and high-resolution LCD TV modules. To prove this experimentally, we investigated the trends of insertion loss, impedance, and crosstalk, which are design parameters of simulation-based FPCs, and designed four FPC samples assuming their application to the intra-panel interface module of a real 75-inch LCD TV. Then, based on the measured S-parameter model, the SI performance was verified and compared by measurement and simulation to demonstrate the validity of the proposed design guidelines. In conclusion, to achieve the SI characteristics of FPCs in LCD TV modules, it is necessary to consider minimizing insertion loss and mitigating crosstalk more than any other electrical performance by enabling the differential P/N pairs to have a strong coupling relationship.

Harmonic injection of domestic nonlinear loads in Ghana's power distribution system: analysis and mitigation using a low-cost notch filter

Due to global efforts to save energy, digital light processing (DLP) and direct view televisions (DVTVs) are being replaced by energy-efficient liquid crystal display (LCD) and light emitting diode (LED) televisions. However, these energy-efficient appliances cause harmonics to be injected into the power distribution system, posing a threat to power quality. This study investigates the harmonics generated by common domestic appliances, particularly LCD and LED TVs used in homes in Ghana. Field harmonic measurements were taken using a C.A. 8335 Power Quality Analyzer at a selected facility and were then replicated in a simulation using MATLAB/SIMULINK to model the facility's area network capacity of 100-kVA, 11kV/433V. The study proposes a notch filter as a harmonic mitigation technique, which is integrated into the simulation design and found to be effective at reducing total harmonic distortion current to 0.05 % when applied in parallel to nonlinear loads. The study also compares the harmonic distortion generated by LED TVs and LCD TVs, finding that both types generate high levels of distortion.

Quantum Dot Enabled Efficient White LEDs for Wide Color Gamut Displays

AbstractIn recent years quantum dots (QDs) emerge as a powerful building block for liquid‐crystal display (LCD) technology, and they are successfully used in the form of color enhancement films. However, their transition toward efficient and wide color gamut LEDs for backlighting remain as an important challenge, which can decrease the required amount of QDs per TV for orders of magnitude. Herein, QD‐based white LEDs are reported that can simultaneously operate with a high external quantum efficiency (EQE) of 39.8% and a wide NTSC color gamut coverage of 133.3%. For red‐emitting spectral range, giant CdSe/CdS core/shell QDs are synthesized via hot injection method, and it is observed that 20 monolayers of CdS shell can lead to a near‐unity photoluminescence quantum yield (PLQY) of 98%. In addition, green‐emitting CdZnSeS/ZnS alloyed core/shell QDs show a PLQY of 97% with a narrow full width at half maximum (FWHM) of 20 nm. To maintain the optical properties of QDs in device architecture, QDs are injected in liquid matrix on blue LED chips and used as the backlighting source for LCD TV that lead to bright and vivid colored images. QD‐based white LEDs with high efficiency and wide color gamut have significant potential for next‐generation display technology.

Birth of the Innovative Overdrive Technology for Liquid Crystal: Paving the Way for Practical Use of LCD Televisions

This article describes our experience developing innovative display technologies with the aim of providing hints for researchers to break away from conventional wisdom. In the 1990s, we focused mainly on liquid crystal display (LCD) technologies for creating and developing the new flat-panel TV market, despite claims that the motion blur problem for LCD TVs could not be solved without materials featuring ultrafast response times. We then discovered that motion blur is not due to a binary response, as was commonly believed at the time, but rather a drastically degraded gray-level response and decreased driving voltage due to electrostatic capacity change according to dynamic rotation of liquid crystal molecules. On the basis of a novel image-lag mechanism, we invented the overdrive method to emphasize the voltage applied to the liquid crystal for only a certain period according to change in picture brightness for high-speed response LCD TVs. This overdrive technology is now a de facto standard technology for LCD TVs, though the time-to-market exceeded 13 years. This article describes why so much time was required and how many issues were resolved to realize this revolutionary innovation.

Benefits of emissive display (OLED TV) from a visual perception

OLED TVs have clear picture quality with a perfect visible angle, perfect black luminance and boast faster response times than LCD TVs. Therefore, the study major contents are Benefits of emitting devices (OLED TV) in terms of visual perception. The first study, we investigated the effects of the peripheral vision luminance level (PVL) and field of view (FOV) on the display brightness perceived by the observer. The results revealed that the lower the black luminance of the display and the smaller the viewing field of the peak luminance image, the higher the relative brightness perceived by the HVS. This result shows the Benefits of OLED TVs that implement perfect black in terms of visual perceived brightness. The second study compared the effects of 4K organic light‐emitting diode (OLED) and liquid‐crystal display (LCD) TVs on human visual task performance when viewing moving pictures. From the results obtained, it was determined that OLED TVs exhibit superior characteristics for hit rate and false alarm rate compared with LCD TVs (non‐emissive‐type). Thus, this study confirms that OLED TVs, given their ultrafast response time characteristics, are superior in terms of moving picture images to LCD TVs.

Effect of moving pictures on visual task performance and fatigue using 4K OLED and LCD TVs

AbstractThis study compared the effects of 4K organic light‐emitting diode (OLED) and liquid‐crystal display (LCD) TVs on human visual task performance and fatigue when viewing moving pictures. In experiments conducted, subjects were asked to locate 35 icons among a total of 276 on‐screen icons at four moving picture speeds. From the results obtained, it was determined that OLED TVs (emissive type) exhibit superior characteristics for hit rate and false alarm rate compared with LCD TVs (non‐emissive‐type). The evaluation results of a simulator sickness questionnaire administered to ascertain fatigue levels also indicated that OLED TVs induce relatively little fatigue at fast‐moving picture speeds of 10 ppf or more compared with LCD TVs. Thus, this study confirms that OLED TVs, given their ultrafast response time characteristics, are superior in terms of moving picture images to LCD TVs.

Potential and Recycling Strategies for LCD Panels from WEEE

Indium is one of the strategically important materials, which have been characterized as critical by various industrialized countries. Despite its high relevance, only low recycling rates are realized. Its main application is in indium tin oxide (ITO), which is used in the production of liquid crystal displays (LCD). However, recovery strategies for indium from LCDs are not yet being implemented in recycling practices. Although LCDs consist of a sandwich compound with additional materials such as glass (80% ± 5%) and polarizer foils (20% ± 5%), recently published recycling approaches focus mainly on the recovery of indium exclusively. This study, first of all, provides information about the quantity and quality of the materials applied in the LCD panels of the various equipment types investigated, such as notebooks, tablets, mobile phones, smartphones, PC monitors, and LCD TVs. The highest indium mass fraction per mass of LCD was determined in mobile phones and the least indium was found in smartphones. Additionally, we found the significant use of contaminating metals like antimony, arsenic, lead, and strontium in the glass fraction. Thus, specific recovery strategies should focus on selected equipment types with the highest indium potential, which is directly related to the sales of new devices and the number of collected end-of-life devices. Secondly, we have developed and successfully tested a novel recycling approach for separating the sandwich compound to provide single output fractions of panel glass, polarizer foils, and an indium concentrate for subsequent recycling. Unfortunately, the strongly varying content of contaminating metals jeopardizes the recycling of this output fraction. Nonetheless, economic recycling approaches need to address all materials contained, in particular those with the highest share in LCD panels such as polarizer foils and panel glass.

Heuristic hybrid genetic algorithm based shape matching approach for the pose detection of backlight units in LCD module assembly

Backlight unit (BLU) and open cell are two critical parts of the liquid crystal display (LCD) module (LCM) which is the most significant component of LCD TV. To place the open cell into a BLU automatically using an assembly robot, this paper proposes a heuristic hybrid genetic algorithm (HHGA) based shape matching approach to detect the pose (orientation and position) of the BLU. The approach takes advantages of line structures of the BLUs to avoid the most time-consuming exhaustive search. Firstly, obtain initial orientation of a BLU by the dominant orientations which can be obtained with the statistical gradient orientation histograms. Secondly, search the optimal pose through the HHGA which mainly consists of local search strategy, crossover strategy, clone strategy, and mutation strategy. Local search strategy is designed according to the rising trend of matching features around the optimal pose and along the lines. Crossover and clone are heuristic strategies designed according to the distribution characteristics of local maxima to produce new meaningful offspring. Mutation is a necessary strategy to keep the diversity of the population. The performance of the proposed approach has been tested on an image database acquired from the LCM assembly lines and compared with standard hybrid GA and exhaustive search by a new statistical indicator. Experimental results show that the proposed approach has a high efficiency within limited time and is suitable for the pose detection of the BLUs.

Potential resource and toxicity impacts from metals in waste electronic devices.

As a result of the continuous release of new electronic devices, existing electronic devices are quickly made obsolete and rapidly become electronic waste (e-waste). Because e-waste contains a variety of metals, information about those metals with the potential for substantial environmental impact should be provided to manufacturers, recyclers, and disposers to proactively reduce this impact. This study assesses the resource and toxicity (i.e., cancer, noncancer, and ecotoxicity) potentials of various heavy metals commonly found in e-waste from laptop computers, liquid-crystal display (LCD) monitors, LCD TVs, plasma TVs, color cathode ray tube (CRT) TVs, and cell phones and then evaluates such potentials using life cycle impact-based methods. Resource potentials derive primarily from Cu, Sb, Ag, and Pb. Toxicity potentials derive primarily from Pb, Ni, and Hg for cancer toxicity; from Pb, Hg, Zn, and As for noncancer toxicity; and from Cu, Pb, Hg, and Zn for ecotoxicity. Therefore, managing these heavy metals should be a high priority in the design, recycling, and disposal stages of electronic devices.

An evaluation of the potential yield of indium recycled from end-of-life LCDs: A case study in China

With the advances in electronics and information technology, China has gradually become the largest consumer of household appliances (HAs). Increasingly, end-of-life (EOL) HAs are generated in China. EOL recycling is a promising strategy to reduce dependence on virgin production, and indium is one of the recycled substances. The potential yield of indium recycling has not been systematically evaluated in China thus far. This paper estimates the potential yield of recycled indium from waste liquid crystal displays (LCDs) in China during the period from 2015 to 2030. The quantities of indium that will be used to produce LCDs are also predicted. The estimates focus on the following three key LCD waste sources: LCD TVs, desktop computers and portable computers. The results show that the demand for indium will be increasing in the near future. It is expected that 350 tonnes of indium will be needed to produce LCDs in China in 2035. The indium recycled from EOL LCDs, however, is much less than the demand and only accounts for approximately 48% of the indium demand. The sustainable index of indium is always less than 0.5. Therefore, future indium recycling efforts should focus on the development of recycling technology and the improvement of the relevant policy.

Optical Properties of the Retro-reflective Polarization Film Fabricated by Stacking Anisotropic and Isotropic Materials

As Liquid Crystal Display (LCD) market with ultra-high definition is growing, high contrast ratio and high light efficiency are required. The anisotropic reflective film can improve light efficiency of the back light unit of LCD TV due to the retro-reflective polarization film, which is named as the double brightness enhanced film fabricated by stacking an optically anisotropic and isotropic layer. We have calculated the transmittance, the reflectance and the polarization degree of the proposed film with respect to the layer number. We also demonstrate the optical performance of the anisotropic reflective film.

Closed loop recycling of plastics containing Flame Retardants

Annually 2.7milliontonnes of plastics containing Flame Retardants (FRs) are globally discarded in Waste Electrical and Electronic Equipment (WEEE). Little is known on the feasibility of closing material loops for FR plastics. Therefore, series of experiments were set up to analyze the feasibility of separating plastics containing FRs from one specific product category, namely End-of-Life (EoL) Liquid Crystal Display (LCD) TVs. The characterization of the housings of this waste stream indicated a concentration of 18wt% Bromine based (Br) FRs and 31wt% Phosphor based (P) FRs, the remainder not containing FRs. With practical tests it was demonstrated that, after disassembly and plastic identification, the co-polymer poly-carbonate (PC)/acrylonitrile-butadiene-styrene (ABS) containing PFR can be recycled in a closed loop system. Based on the determined plastic density distributions and separation efficiencies of optical sorters, a purity of 82% was calculated for PFR PC/ABS separated from EoL LCD TVs after size-reduction (shredding). Performed miscibility tests indicated that for this fraction at least a factor 10 dilution with virgin material is required. In addition, higher waste volumes are required for a size-reduction based treatment to become economically viable and technical challenges still need to be faced, whereas closed loop recycling of PFR PC/ABS from the current waste stream of EoL LCD TVs of different brands in a disassembly based treatment is found to be technically feasible and economically viable under European boundary conditions.

Compromising Emanations of LCD TV Sets

This study attempts to characterize the radiated compromising emanations from four typical television sets with liquid-crystal display (LCD), in particular the predictability of format and timing parameters. Three were found to emit clear ultrahigh frequency radio signals visually related to the displayed image, from the display controller or its low-voltage differential signaling link to the LCD panel. Although the input signals to all four products followed the same TV standard, the timing parameters of their emanations differed substantially. Some also frequency-modulate their pixel clock to improve compliance with electromagnetic-interference limits. All digitally rescale the input image to the respective display size. The frame rate at which the display panel is driven is, if at all, only loosely phase locked to the input signal. These observations have implications for eavesdroppers, for the design of test standards to limit compromising emanations from video displays, and for the practicality of detecting the mere presence of an active television receiver by correlating the emanations of the circuitry driving its display panel with a known broadcast TV input signal.

LCD brightness decay due to particulate contamination of back light unit

So far, particulate contamination problems occurring in cleanroom environments have been intensively investigated by considering the product yield in semiconductor manufacturing or liquid crystal display (LCD) manufacturing. This study, however, focused on the particulate contamination problem causing the degradation of LCD TVs run in common environments. A field test was conducted by running a LCD TV in an office room for 60 days in order to collect and analyze the particles contaminating the backlight unit (BLU) of the LCD TV. Based on the field test result, soot particles were generated to simulate the contaminant particles, and an accelerated test was performed by exposing the LCD TV to a soot aerosol of relatively high concentration. As the exposure time was increased, the degree of particulate contamination of the BLU became more severe, and the decay rate of the LCD brightness increased. As a result, the particulate contamination of the BLU was found to greatly affect the decay rate of the LCD brightness. A numerical simulation was performed to elucidate the mechanism of particle influx into the BLU and to predict the particle deposition pattern. The contaminant particles could enter into the BLU through the gaps on the BLU casing due to the air flow induced by natural convection in the BLU. The particles were thought to have been deposited on the walls in the BLU, especially at the corner regions.

A New Approach to Estimating Product Lifetimes: A Case Study of an LED Based LCD TV

Estimating the economic life of a technology is the first important prerequisite step in the feasibility analysis of technology-based business. Many empirical studies have concentrated on patents data to estimate the time period for a technology. However, it is recommended to estimate it along with qualitative considerations of future technological and market conditions. In this regard, little is known about how approaches are applied. This paper aims to establish a structural framework of estimating the lifetime of a technology by integrating the outputs of an analysis of the determinants in each transition of a product life cycle. We describe an illustrative case about a light emitting diode (LED) backlight unit (BLU) technology for the liquid crystal display (LCD) TV. The framework allows valuators and experts to estimate a technology lifetime by using multidimensional factors.

ZnO-based Transparent Electrodes for LCD TVs

20-in. liquid crystal display (LCD) TVs were successfully fabricated with Ga-doped ZnO (GZO) transparent electrodes on the RGB color filter and conventional indium tin oxide transparent electrodes on the thin film transistor pixel array. The high optical transmittance of the GZO film is beneficial for the color representation characteristics of LCD TVs. A technique for the formation of GZO fine patterns was also developed using wet-chemical etching and the pH values of chemicals used for the photolithography and etching processes were optimized. Line/space patterns widths of 2 um/2 um were accomplished using the optimized patterning technique.

Liquid crystal display panel fabricated in dual mode

The current panels for liquid crystal display (LCD) TV sets are all characterized by pins placed on two sides. To manufacture one type of panel, a dedicated mask is needed, and the production line should be started once. Moreover, the whole panel needs to be removed if a dead pixel is found. If the panel, however, will first be fabricated with pins placed on four sides and then divided by a cross-cut into four equal-sized panels with pins placed on two sides, one set of masks can be used to manufacture two types of LCD panels, which was referred to by the authors as dual mode. In this paper, the concept of the dual mode and its differences from the conventional way of producing panels are introduced. Its advantages in boosting production efficiency, improving the product's good rate, and lowering the production cost are also described based on case studies. Of particular importance is the fact that the dual mode is very suitable for the trial production of very-large-area LCD TV sets.

Digital Lamp Balance System With Individual Lamp Current Control Capability for an LCD TV

A digital lamp balance system that equalizes lamp current of liquid crystal display (LCD) backlight is implemented in this letter. The proposed digital balance circuit consists of a balance switch which is in series with the lamp and a dc-blocking capacitor which also acts as a ballast capacitor for parallel lighting. The parasitic capacitance of the balance switch is used as parallel impedance which makes the lamp current decrease. Microcontroller unit controls each lamp current by changing the pulsewidth modulation duty ratio of a balance switch. The specified circuit, analysis, balance principles, and experimental results of the proposed system will be presented for a 46-in LCD TV.

Measuring innovations in the Japanese LCD TVs using market data

Quality-adjusted price indexes based on a discrete choice model and a weighted hedonic function are estimated using market data for Liquid Crystal Display (LCD) TVs obtained from a large Internet price comparison service in Japan. Implicit values of attributes were used to unify marginal values of attributes into a scalar quality measure, and thus, we measure innovations by the price shift while controlling the levels of the attributes. We also report estimates on welfare gains through the discrete choice approach.

Angular dependence of the performance of stereoscopic liquid‐crystal‐display (LCD) television using shutter glasses (SG)

Abstract— 3‐D cross‐talk typically represents the ratio of image overlap between the left and right views. For stereoscopic LCDs using shutter‐glasses technology, 3‐D cross‐talk for stereoscopic LCD TV with a diagonal size of 46 in. and vertical alignment (VA) mode was measured to change from 1% to 10% when the stereoscopic display is rotated around the vertical axis. Input signals consist of the left and right images that include patterns of different amounts of binocular disparity and various gray levels. Ghost‐like artifacts are observed. Furthermore, intensities of these artifacts are observed to change as the stereoscopic display is rotated about the vertical axis. The temporal luminance of the LCD used in stereoscopic TV was found to be dependent on the viewing direction and can be considered as one cause of the phenomenon of angular dependence of performance for stereoscopic displays.