Liquid Crystal Display Screen Research Articles

Automatic Testing Technology of BTB Liquid Crystal Display Advanced Fault Detection in Smart Meter for Smart Machine

In smart meter technology, the reliability of Backplane to Bezel (BTB) Liquid Crystal Displays (LCDs) is crucial for efficient functioning within intelligent grid systems. Defects in these LCD screens can significantly impact overall smart meter performance, necessitating effective detection methods for proper management and utilization. Current detection approaches, which combine manual and automatic methods based on machine vision, have shown unsatisfactory performance. This research addresses this challenge by proposing a novel method for advanced fault detection in BTB LCDs of smart meters, Automatic Testing Technology of BTB Liquid Crystal Display Advanced Fault Detection in Smart Meter for smart machine (BTB-LCD-FD- MCDSGAN) is proposed. The study begins by collecting datasets specifically tailored for LCD screen localization and defect detection. To enhance data quality, a Window Adaptive Extended Kalman Filter (WAEKF) is applied during preprocessing for noise removal. Feature extraction follows, utilizing Parameterized Multi Synchrosqueezing Transforms (PMST) with a primary focus on Gray Level Co-occurrence Matrix features. These extracted features serve as input for classification by a Multimodal Contrastive Domain Sharing Generative Adversarial Network (MCDSGAN), categorizing defects into five types likes normal display, no display, abnormal display, liquid crystal rupture, and incomplete display. Furthermore, the proposed method optimizes the MCDSGAN weight parameter using the Red Fox Optimization Algorithm (RFOA) to achieve accurate LCD fault defect prediction. The entire approach is implemented in Python, performance metrics likes accuracy, precision, recall, F-score, computational time are thoroughly analyzed. Performance of proposed BTB-LCD-FD-MCDSGAN approach attains 20.89%, 33.67% and 25.98% high accuracy, and 17.98%, 23.78% and 33.45% higher recall compared with existing methods such as automatic detection of display defects for smart meters depend on deep learning (AD-AM-DL), deep learning-enabled image content-adaptive field sequential color LCDs by mini-LED backlight (DL-AFSC-LCD) and new multi category defect detection method depend on convolutional neural network technique for TFT-LCD panels (MDF-CNN-LCD), methods respectively.

Liquid crystal monomers in ventilation and air conditioning dust: Indoor characteristics, sources analysis and toxicity assessment

Indoor dust contaminated with liquid crystal monomers (LCMs) released from various commercial liquid crystal display (LCD) screens may pose environmental health risks to humans. This study aimed to investigate the occurrence of 64 LCMs in ventilation and air conditioning filters (VACF) dust, characterize their composition profiles, potential sources, and associations with indoor characteristics, and assess their in vitro toxicity using the human lung bronchial epithelial cells (BEAS-2B). A total of 31 LCMs with concentrations (ΣLCMs) ranging from 43.7 ng/g to 448 ng/g were detected in the collected VACF dust. Additional analysis revealed the potential interactions between indoor environmental conditions and human exposure risks associated with the detected LCMs in VACF dust. The service area and working time of the ventilation and air conditioning system, and the number of indoor LCD screens were positively correlated with the fluorinated ΣLCMs in VACF dust (r = 0.355 ∼ 0.511, p < 0.05), while the associations with the non-fluorinated ΣLCMs were not found (p > 0.05), suggesting different environmental behavior and fates of fluorinated and non-fluorinated LCMs in the indoor environment. Four main indoor sources of LCMs (i.e., computer (37.1%), television (28.3%), Brand A smartphone (21.2%) and Brand S smartphone (13.4%)) were identified by positive matrix factorization-multiple linear regression (PMF-MLR). Exposure to 14 relatively frequently detected LCMs, individually and in the mixture, induced significant oxidative stress in BEAS-2B cells. Among them, non-fluorinated LCMs, specifically 3cH2B and MeP3bcH, caused dominant decreased cell viability. This study provides new insights into the indoor LCMs pollution and the associated potential health risks due to the daily use of electronic devices.

Release Behavior of Liquid Crystal Monomers from Waste Smartphone Screens: Occurrence, Distribution, and Mechanistic Modeling.

Liquid crystal display (LCD) screens can release many organic pollutants into the indoor environment, including liquid crystal monomers (LCMs), which have been proposed as a novel class of emerging pollutants. Knowing the release pathways and mechanisms of LCMs from various components of LCD screens is important to accurately assess the LCM release and reveal their environmental transport behavior and fate in the ambient environment. A total of 47, 43, and 33 out of 64 target LCMs were detected in three disassembled parts of waste smartphone screens, including the LCM layer (LL), light guide plate (LGP), and screen protector (SP), respectively. Correlation analysis confirmed LL was the source of LCMs detected in LGP and SP. The emission factors of LCMs from waste screen, SP, and LGP parts were estimated as 2.38 × 10-3, 1.36 × 10-3, and 1.02 × 10-3, respectively. A mechanism model was developed to describe the release behaviors of LCMs from waste screens, where three characteristics parameters of released LCMs, including average mass proportion (AP), predicted subcooled vapor pressures (PL), and octanol-air partitioning coefficients (Koa), involving coexistence of absorption and adsorption mechanisms, could control the diffusion-partitioning. The released LCMs in LGP could reach diffusion-partition equilibrium more quickly than those in SP, indicating that LCM release could be mainly governed through SP diffusions.

Designing of automated paralysis patient healthcare system

We come across hospitals and non-profit organizations that care for people with paralysis who have had all or partof their body incapacitated by the paralysis attack. Due to a lack of motor control by their brain, these individualsare typically unable to communicate their requirements because they are neither able to speak clearly nor use signlanguage. In such a circumstance, we suggest a system that enables a disabled person to display a message overthe liquid crystal display (LCD) screen by merely moving any part of his or her body that is capable of motion. Thissolution also addresses the circumstance where the patient is alone and no one is available to care for him or her,sending an Internet of things (IoT) message instead of a short messaging service (SMS).The system operates by interpreting the user part’s tilt direction. By grasping the device in the fingers of the movinghand, the device’s operation is demonstrated. To communicate a message, the user only needs to tilt the gadgetat a specific angle. The message is conveyed differently depending on the way the gadget is tilted. Here, thestatistics of motion are measured using an accelerometer. This information is then transmitted to a microcontroller.The microcontroller analyzes the data and displays the specific message in accordance with the input received. Theassociated message is now shown on the LCD screen by the microcontroller. As soon as it receives a motion signalfrom the accelerometer, it also emits a siren and a message. If no one was available to respond to the message onthe LCD, then the patient might opt to tilt the device for an additional period of time, which would cause an SMSto be sent via IoT to the patient’s registered caretaker with the message the patient wishes to communicate.

Correlation study of physical and mechanical properties of concretes with crushed LCD glass

The need to increase the sustainability of the construction industry is leading to the search for alternative sources of raw materials. Liquid crystal display (LCD) screens have been used for many years and are also rapidly ageing as a result of fast development. Therefore, the use of waste from LCD screens is an interesting avenue for the construction industry. This paper presents a very practical study of the use of old LCD screen of ground material to replace various fine aggregates. Fifteen concrete mixes of different strength levels and with different amounts of LCD powder were prepared. These are C20, C25, and C35 grade concretes, all of which contain LCD powder in quantities ranging from 15% to 60%. Results of density, compressive strength, and tensile strength at 7 and 28 days after concreting. The results are correlated with the number of replacement components and are also correlated with each other. The data presented to improve our understanding of the practical application of LCD waste aggregate in concrete. The results show that the amount of LCD powder has a direct linear effect on the compressive strength and also a direct lognormal effect on the tensile strength of concrete.

High-accuracy camera calibration method based on coded concentric ring center extraction

In the field of three-dimensional (3-D) metrology based on fringe projection profilometry (FPP), accurate camera calibration is an essential task and a primary requirement. In order to improve the accuracy of camera calibration, the calibration board or calibration target needs to be manufactured with high accuracy, and the marker points in calibration image require to be positioned with high accuracy. This paper presents an improved camera calibration method by simultaneously optimizing the camera parameters and target geometry. Specifically, a set of regularly distributed target markers with rich coded concentric ring pattern is first displayed on a liquid crystal display (LCD) screen. Then, the sub-pixel edges of all coded bands radial straight lines are automatically located at several positions of the LCD screen. Finally, the sub-pixel edge point set is mapped into parameter space to form a line set, and the intersection of the lines is defined as the center pixel coordinates of each target point to complete the camera calibration. The simulation and experimental results verify that the proposed camera calibration method is feasible and easy to operate, which can essentially eliminate the perspective transformation error to improve the accuracy of camera parameters and target geometry.

Large size lenticular shaped phosphors-in-glass by Isobam-APS gel casting to act for converting and condensing in LCD projector

White light diodes (WLEDs) composed of blue chip and phosphor-converter are widely used in liquid crystal display (LCD) projectors as backlights. And it often needs a condenser lens to irradiate white light onto the LCD screen. In this paper, a large size lenticular shaped phosphors-in-glass (PiG) was prepared by Isobam-APS gel casting for the first time. The PiG could act for converting and condensing in LCD projector. Then a rectangular light spot similar to the shape of LCD screen was obtained to reduce the loss of light. The maximum temperatures of the chip and PiG were 62.1 °C and 57.3 °C respectively after working for 600 s and gradually stabilized by simulation. It was proved that simulation result was reliable through comparing with the actual measured value and the lenticular shaped PiG had good heat dissipation capacity for its large area. In conclusion, this is a successful application of PiG in LCD projector, which has guidance and promoting effect.

Selective Leaching and Recovery of Er, Gd, Sn, and In from Liquid Crystal Display Screen Waste by Sono-Leaching Assisted by Magnetic Separation.

We report a facile, economic, and ecofriendly method for selective recovery of Er, Gd, Sn, and In from liquid crystal display (LCD) screen wastes by ultrasound-assisted leaching, followed by magnetic separation. Thermodynamic analysis showed that the pyrophosphate ion is an excellent leaching agent for Er, Gd, and In at pH values below 8. Dissolved screen waste powder was subjected to leaching at room temperature using aqueous solutions of 0.05 M of sodium pyrophosphate (Na4P2O7) as the leaching agent; hydrogen peroxide (H2O2) (3 v/v %) was added as an auxiliary reducing agent, and an ultrasonic source was used in the process. Once completed, magnetic separation was applied to the leached residue. The average contents of Er, In, Sn, and Gd in the LCD screen were found to be 477, 2422, 835, and 93 mg·kg–1, respectively, of which 93, 97, 72, and 99% were selectively recovered from the waste material by this method at pH 3 after 2 h of leaching. The proposed method emerges as an easy and selective process for leaching Er from LCD screen wastes and concentrating In, Sn, and Gd in a separable magnetic solid.

The recycling of pure metallic indium from waste LCD screens by a combined hydro-electrometallurgical method

The Liquid Crystal Display (LCD) panels were removed and crushed to be leached. Sulphuric acid of 0.25 M H2SO4 was found best for relatively fast reactions and selectivity, recovering >99% of the indium from the indium‑tin oxide (ITO) layers, while >95% of the tin content was left in the solid residue. As potential impurities, Sn, Fe, Mn, Ni, Zn, Bi, Pb, Al and Cu were analysed in the solutions and in the final product. Synthetic solutions of larger volumes corresponding to the obtained leachate were used for developing the purification and metal recovery steps. Metallic indium was extracted selectively from the solution by cementation on Al plates. The purity of the primary indium deposit was controlled by increasing the temperature to 50–60 °C and keeping the pH in the 0.25–0.5 range, while the aluminium consumption was close to the stoichiometric value. The cemented sponge was vacuum-melted to produce an indium anode block of >99.9% purity for electrorefining. According to the galvanostatic and potentiodynamic results, the optimal electrolyte conditions were found as 50 g/dm3 In, 1 M free Cl− ions, pH 1. The cathodic deposition of Zn, Mn, and Fe was negligible; however, the prior removal of Cu and Sn from the solution is required for producing high-purity indium. Generally, increasing the cathodic current density in the range of 150–600 A/m2 enhanced the purity of the cathodes, while a maximum pH 2 value should be assured. Chloride ion concentration strongly influences the deposit morphology.

Analysis of Melt Front Behavior of a Light Guiding Plate during the Filling Phase of Micro-Injection Molding

When the size of a liquid crystal display (LCD) increases, the light guiding plate (LGP) as the main part of the LCD must adopt a wedge-shaped plate to reduce its weight (the thickness of the LGP decreases because of this) and guide the light to the LCD screen. Micro-injection molding (MIM) is commonly used to manufacture LGPs. During the filling phase of MIM, the entire entering polymer melt front of the LGP should reach the end of the mold cavity at the same time. In this way, there will be no shrinkage or warpage of the LGP in its subsequent application, but it is difficult for the wedge-shaped LGP to meet these requirements. Therefore, the authors hoped to investigate MIM process parameters to change this situation. Otherwise, the LGP is easily deformed during the manufacturing process. Flow characteristics of LGPs were investigated during the filling phase of MIM in this study. Experimental and 3D numerical simulations were used to analyze the hysteresis, i.e., the advance of the polymer melt front of the LGP in MIM. Study results showed that a low injection speed caused a hysteresis effect of the plastic melt front, the solution was to increase the injection speed to improve the situation and an injection speed of 10 cm/s could achieve uniformity of the melt front in MIM. The research results showed that the filling situation of the LGP of MIM in the experiment was very close to that of the 3D numerical simulation.

A Biosensor Platform for Point-of-Care SARS-CoV-2 Screening.

The COVID-19 pandemic remains a constant threat to human health, the economy, and social relations. Scientists around the world are constantly looking for new technological tools to deal with the pandemic. Such tools are the rapid virus detection tests, which are constantly evolving and optimizing. This paper presents a biosensor platform for the rapid detection of spike protein both in laboratory conditions and in swab samples from hospitalized patients. It is a continuation and improvement of our previous work and consists of a microcontroller-based readout circuit, which measures the capacitance change generated in an interdigitated electrode transducer by the presence either of sole spike protein or the presence of SARS-CoV-2 particles in swab samples. The circuit efficiency is calibrated by its correlation with the capacitance measurement of an LCR (inductance (L), capacitance (C), and resistance (R)) meter. The test result is made available in less than 2 min through the microcontroller’s LCD (liquid-crystal display) screen, whereas at the same time, the collected data are sent wirelessly to a mobile application interface. The novelty of this research lies in the potential it offers for continuous and effective screening of SARS-CoV-2 patients, which is facilitated and enhanced, providing big data statistics of COVID-19 in terms of space and time. This device can be used by individuals for SARS-CoV-2 testing at home, by health professionals for patient monitoring, and by public health agencies for monitoring the spatio-temporal spread of the virus.

IoT Based Solar Power Monitoring Using Arduino

Abstract: This project aims to develop a measurement of solar energy using Arduino Board technology. In this research, four parameters that been measured are temperature, voltage and current. The temperature was measured using temperature sensor. The voltage was measured using the voltage divider because the voltage generated by the solar panel is large for the Arduino as receiver. Lastly for the current was measured using the current sensor module that can sense the current generated by the solar panel. These parameters as the input value for the Arduino and the output was display at the Liquid Crystal Display (LCD) screen. The LCD screen display output of the temperature, the light intensity, the voltage and the current value. The purpose of Arduino to convert the analog input of parameter to the digital output and display via LCD screen. Other than that, this project also involves with a design to ensure that device case is easy to be carry around. Application of IoT is proving beneficial for monitoring renewable energy generation. This application of IoT uses system based on Arduino to monitor parameters of the solar panel. The solar panel is monitored by the system continuously and the power output is transmitted over the internet to the IoT Network. It now uses an effective Interface to display these solar panel parameters to the user and it also alerts user when the outcome falls underneath the cut-off points specified. This makes, distantly monitoring of solar power plants more convenient and the best output of power is guaranteed. Keywords: Internet of Things (IOT), Power Output, Renewable Energy, Solar Energy, Solar Panel

Progress of Backlight Devices: Emergence of Halide Perovskite Quantum Dots/Nanomaterials

The technology behind the display is becoming ever more prevalent in our daily lives. It has many applications, including smartphones, tablets, desktop monitors, TVs, and augmented reality/virtual reality devices. The display technology has progressed drastically over the past decade, from the bulky cathode ray tube to the flat panel displays. In the flat panel displays, the liquid crystal display (LCD) and organic light-emitting diodes (OLEDs) are the two dominant technologies. Nevertheless, due to low stability and color tunability, OLEDs remain behind the LCDs. The LCD screen has a backlight, usually a white LED, which comprises a blue LED covered with a red and green enhanced layer (color-converting layers). Although InP/CdSe QDs attracted more attention due to their solution processability and better color gamut than the previous technologies, the complexity of their synthesis was still an obstacle to their commercialization. Later, the emergence of perovskite with highly intense and tunable PL emission, high color purity, and low-cost synthesis route attracted the attention of display researchers. Owing to the relatively higher performance of perovskite quantum dots (PQDs) than that of bulk (3D) perovskite in backlit display devices, these PQDs are being used for high color contrast and bright display devices. Furthermore, the color gamut for PQDs was observed as 140% of the NTSC standard, that is, close to that of the commercial OLED devices. In this review, we have discussed the progress of display technologies with a clear classification of the pros and cons of each technology. Also, the application of perovskite QD/nanomaterials in LCD backlit devices has been discussed, and the future direction of further improvement in their stability and performance has been listed.

Application of Arduino Devices in various IOT Application

In this paper, v segribe the wireless sensor network system is the next open source hardware we've graded or raspberry arduino refers to an open source electronic operating system or board and the software used to program it. Arduino is designed to give electronic devices access to artists, designers, entertainment enthusiasts and those interested in creating interactive objects or contexts. Arduino boards input sensor in light, a finger or twitter message read on a button -and turn it into a release- running a motor, turning on the led, posting anything online. To the microcontroller on board a set of instructions what to do by sending. Little education in this article run the mobile robot complete of systems provides overview. The arduino is easy to use and a greater number named for the sensors. In fact, in every application new skills are added, also this hardware, hardware services i / o bespoke with target, point-to-point relationships for protocols are defined primarily. Voltage is measured using voltage. Separator, because generated by the solar panel voltage for arduino larger than the receiver. Finally, created by the solar panel current sensor current is measured using volume. These parameters are arduino and as the input value for the output the liquid crystal display (LCD) is displayed on the screen. LCD screen temperature, light intensity, shows voltage and current value output. Arduino analog of the parameter the purpose of the input is to quickly convert to digital output, LCD screen displays via arduino, it is one of the most popular microcontrollers one will be used in robotics .different types of arduino there are microcontrollers, they are about design and features not only that, but the size and processing skills also vary. Completely different chips, however there are only two models in use: fixed and mega. Arduino board, this is yours when creating products of the hardware you work with is a part of. Is the arduino IDE software running on your computer? A sketch you upload on the arduino board (a small computer program) create IDE are using. More than a decade with intensive research and development, wireless sensor network for many innovative applications technology a emerges as a viable solution

Surface Shape Distortion Online Measurement Method for Compact Laser Cavities Based on Phase Measuring Deflectometry

Conventional phase measuring deflectometry (PMD) takes up a large measurement space and is not suitable for compact online measurement, as the liquid crystal display (LCD) has to be placed in parallel with the mirror under test. In this paper, a compact online phase measuring deflectometry (COPMD) with the LCD screen set perpendicular to the mirror under test is presented for surface shape distortion real-time measurement. The configuration of the COPMD in an enclosed laser cavity is proposed, and the principle of the method is theoretically derived by using the vector-form reflection law. Based on the analysis model, the fringe modulation regulation of the LCD is revealed, and the measurement errors caused by misalignments of the components are illustrated. The validity and flexibility of the COPMD method are verified in the experiment by using a single-actuator deformable mirror as the mirror under test and the PMD method as the comparison. The proposed COPMD method remarkably expands the application range of the conventional PMD method, as it could make efficient use of compact space and is applicable for real-time measurement in enclosed laser facilities and assembled laser systems.

A Novel Strategy for Monitoring a PV Junction Box Based on LoRa in a 3 kW Residential PV System

Recently, 3 kW residential PV (Photovoltaic) junction boxes have mainly been installed on the roof or outer wall of building. Wired and wireless monitoring systems are being implemented by RS-485 and WIFI/IoT. However, conventional monitoring systems have a communication limitation according to the distance and environment. It cannot receive any information when a failure of the PV junction box occurs. Therefore, there is a need for a strategy to determine whether the fuse and diode in the PV junction box are faulty through voltage and current sensors. In this paper, we propose a novel strategy for monitoring PV junction boxes, based on LoRa (Long Range). The TTGO LoRa32 V2.0 module with LoRa and various input and output ports is utilized. The wireless TX module transmits various data collected from the PV junction box to the RX module in real time. In addition, the RX module displays the received data on an LCD (Liquid Crystal Display) screen so that the user can intuitively identify it, and the data is recorded on the internal storage device or database in the web server. The manufactured PV junction box monitoring system was tested under a 3 kW PV system. Additionally, communication reception has stable signal intensity overall, both indoors and outdoors. In particular, it shows excellent characteristics in maintaining RSSI (Received Signal Strength Indicator) &gt; −99 dBm and PER (Packet Error Rate) &lt; 2.7%, up to a radius of 200 m, even in NLOS (Non Line-Of-Sight) environments. Although some packet loss occurred, it was confirmed that invisible communication was possible up to 300 m.

Recaptured image forensics based on local ternary count of high order prediction error

With the advancement in image display technology and the widespread use of various image acquisition devices, recapturing high-quality images from high-fidelity LCD (liquid crystal display) screens becomes very convenient and easy. These recaptured images pose serious threats on current image forensic technology and intelligent recognition systems. In order to solve these security problems, we propose a recaptured image forensics method based on local ternary count (LTC) of high order prediction error. Specifically, given an image, the second-order difference maps on different directions are calculated in HSV color space for the original image and its average pooled version. Then, we calculate the prediction error maps from these second-order difference maps through a linear predictor. Finally, the normalized LTC histograms of all the downsampled versions of the obtained prediction error maps are calculated as features for training and testing. Single database experiments demonstrate that our proposed method performs very similar with the state-of-the-art traditional method on the most difficult-to-detect ICL-COMMSP database with obvious less execution-time and lower feature dimension. Meanwhile, it performs very close to the existing well-performed deep learning based method on all the databases, which verifies the effectiveness of our proposed features. Besides, mixed database experiments verify the superiority on generalization ability of our proposed method. Moreover, it is robust to JPEG compression.

Reducing lateral stair-stepping defects in liquid crystal display-based vat photopolymerization by defocusing the image pattern

Vat photopolymerization-based additive manufacturing (AM) technology has emerging success in efficiently fabricating complex and high-resolution objects. However, the lateral and vertical stair-stepping defects limit vat photopolymerization in manufacturing smooth surfaces, such as optical components. Vertical stair-stepping was mitigated by thinner layer thickness or layer-less fabrication. It is still challenging to reduce the lateral stair-stepping defects caused by the pixelated projection pattern, especially for Liquid Crystal Display (LCD) projection whose pixels are disconnected. To tackle this lateral stair-stepping issue, we propose to defocus the curing image pattern by increasing the gap between the LCD screen and the resin vat. This gap intentionally blurs the disconnected pixels to create a continuous and smooth projection pattern. Experiments verified that the smoothened LCD pattern led to an average 81.2% reduction in surface roughness, which was much more effective than grayscale pixels. The gap between the LCD screen and the resin vat also enabled blowing air to dissipate the heat from LCD and the resin polymerization, reducing the part distortion and printing failure due to the thermal stress. The present approach improved the surface roughness and paved the way for vat photopolymerization in fabricating smooth micro-optics, microfluidic channels, and functional curved surfaces.

Blue Light Intensity in Organic Light-Emitting Diode and Liquid-Crystal Display Televisions

Exposure to artificial blue light from screens, especially at evening or nighttime hours, can suppress melatonin production, throw the circadian rhythm off balance, and lead to general difficulty falling asleep. This study sought to investigate the difference in blue light intensity in organic light-emitting diode (OLED) and liquid-crystal display (LCD) screens, specifically in the form of televisions. An observational and quasi-experimental method was used, using a photometer to measure light intensity and a longpass optical filter to block out light ranging from 415 to 515 nanometers, serving as the wavelength of blue light for this study. Two televisions—one OLED and one LCD—were used, with five colors being displayed on each one, one at a time. The LCD television contained more relative blue light than the OLED television for four out of the five colors displayed. On average for all colors, the LCD television emitted 24.92% more blue light than the OLED television, relative to their overall brightnesses. Limitations in scope and the potential of confounding variables interfering with data prevent any definitive conclusions from being drawn, however this study still contributes to the current body of knowledge with evidence towards a trend of lessened blue light intensity in OLED screens compared to LCD screens, which correlates with speculation by other researchers. This study sets the ground for future research investigating the potential of OLED technology in lowering exposure to blue light, thus lessening the negative impacts it can have on individuals.

Investigation of indium and other valuable metals leaching from unground waste LCD screens by organic and inorganic acid leaching

• Investigation of indium extraction from waste LCD screen. • Variation of the indium amount on different parts of the LCD screens. • Effect of inorganic and organic acid types on the selective indium leaching. • Reaching relatively high indium concentration while minimizing impurities by H 2 SO 4. • Increasing the indium concentration by reusing the leachate. Indium (In) is the indispensable part of liquid crystal display (LCD) screen which is applied as a thin semiconductor layer on the surface mainly in the form of indium tin oxide (ITO), and feasible end-of-life recycling of indium from this electronic devices is technologically challenging. The present study investigates the recovery of indium from spent untreated liquid crystal display (LCD) screen by inorganic and organic leaching. Critical process parameters such as effects of different acids, leaching duration, reusability of acidic solution and both sides of the organic layers on the LCD were studied to optimize the indium leaching from the waste screen. The efficiencies of inorganic acids (nitric and sulfuric) and organic acids (citric, glycolic, L-ascorbic, maleic and DL-tartaric) to leach metals on LCD were investigated in different leaching duration from 3 to 168 h. Extracted metal concentrations and dissolved organics are characterized by inductively coupled plasma with mass spectrometry and total organic carbon analyser, respectively. The results indicate that over 90% extraction of indium and the lowest amount of other impurities can be achieved using 1 M H 2 SO 4 for a leaching period of 48 h. Moreover, similar results could reach with 1 M HNO 3 , while organic acids were less successful under these conditions. Overall, the indium amount could reach up to 69 mg/kg ITO glass for the front and 31 mg/kg ITO glass for the back side glass. However, relatively high amount of organic layer from LCD screen dissolves in nitric acid solution up to 4000 mg TOC /l, which can affect the further stages of a recycling process. Besides, aluminium, zinc and tin were identified as the elements with the highest amount with indium in the leachate. All these elements were found in both, glass and organic layer of the LCD screen. Although metals from LCD screen have limited solubility in organic acids, specifically tartaric acid has a selective extraction behaviour for molybdenum. By reusing the leachate for further leaching processes, the concentration of indium could be increased constantly up to five times, which indicates that it is possible to increase the indium concentration to the industrially processable amount.