China
Africa
Explore chapters and articles related to this topic
Transparent Electrode for OLEDs
Published in Zhigang Rick Li, Organic Light-Emitting Materials and Devices, 2017
The demand for more user-friendly displays is propelling efforts to produce head-worn and handheld devices that are flexible, lighter, more cost-effective, and more environmentally benign than those presently available (see Chapter 8 for more details). Flexible thinfilm displays enable the production of a wide range of entertainment-related, wireless, wearable computing, and network-enabled devices. The display of the future requires that it should be thin in physical dimension, have small and large formats, flexible, and full color at a low cost. These demands are sorely lacking in today’s display products and technologies such as the plasma display and LCD technologies. OLEDs have the potential to replace LCDs as the dominant flat-panel displays. This is because OLEDs have high visibility by self-luminescence, do not require backlighting, and can be fabricated into lightweight, thin, and flexible displays. OLED stands out as a promising technology that can deliver the above challenging requirements.
Real-Time Tracing and Alerting System for Vehicles and Children to Ensure Safety and Security, Using LabVIEW
Published in S. Poonkuntran, Rajesh Kumar Dhanraj, Balamurugan Balusamy, Object Detection with Deep Learning Models, 2023
R. Deepalakshmi, R. Vijayalakshmi
In this system, a PIC16F877A microcontroller has been used. The system consists of three units, bus unit, school unit and parent unit. The bus unit consists of an RFID reader, fire sensors and SMS to alert messages to parents when their children board or leave the bus. A fire sensor will be placed within the bus unit to detect fire and issue alert messages by giving the location of the bus using IoT. The school unit consists of an RFID reader and GSM Module. The entire data in two units will be processed by using a PIC16F877A microcontroller. This processor has advantages like the total number of pins is 40, and there are 30 pins for input and outputs, 368 RAM bytes, 5MIPS CPU speed, and 8 channels of 10-bit ADC converter. In this system fire sensor is used to detect fire accidents. If any fire accident occurs, the alert message will be sent to the school unit and parents with the help of IoT and SMS. Each student unit consists of an individual RFID tag; with the help of the RFID tag, the parents and school units can receive an alert message. The information of the RFID tag is read by the RFID reader. The reader transmits the corresponding information. The RFID tag is used to send an alert message like a person’s location and speed of the bus to their respective parents. In this system, IoT is used to send the alert message to the parents if their respective child is getting on or off the bus with the help of RFID tag and reader. LCD stands for liquid crystal display, a flat panel display technology commonly used in TVs and computer monitors. It is also used in screens for mobile devices, such as laptops, tablets, and smartphones. The backlight in liquid crystal display provides an even light source behind the screen. This light is polarized, meaning only half of the light shines through to the liquid crystal layer. The liquid crystals are made up of a part solid, part liquid substance that can be “twisted” by applying an electrical voltage to them. They block the polarized light when they are off, but reflect red, green, or blue light when activated. ADC Power Supply Unit (commonly called a PSU) deriving power from the AC mains (line) supply performs a number of tasks: It changes (in most cases reduces) the level of supply to a value suitable for driving the load circuit. It produces a DC supply from the mains (or line) supply AC sine wave. It prevents any AC from appearing at the supply output. Power supplies in recent times have greatly improved in reliability but, because they have to handle considerably higher voltage currents than any or most of the circuitry they supply, they are often the most susceptible to failure of any part of an electronic system. GPS is a satellite navigation system used to determine the ground position of an object. Each GPS satellite broadcasts a message that includes the satellite’s current position, orbit, and exact time. A GPS receiver combines the broadcasts from multiple satellites to calculate its exact position using a process called triangulation.
Fluorination of 2,5-diphenyl-1,3,4-oxadiazole enhances the electron transport properties for OLED devices: a DFT analysis
Published in Phase Transitions, 2022
Aditya Tiwari, Madan Singh Chauhan, Dipendra Sharma
During the last few decades, progress in organic light-emitting diodes (OLEDs) has been highly motivated by the first electrical conductivity observation by Heeger’s group in 1977 in the field of organic electronics [1–4]. The interface of electron transport materials within the OLED layers plays a vital role in determining the characteristics of OLED devices. In recent years, OLEDs got much attention in scientific and industrial research due to their fascinating characteristics of having color variety, lightweight, high brightness, better optical transparency, quick switching time, low operational voltage, high flexibility and low cost, which paved the way for its multifarious application in lighting technologies together with the next-generation flat-panel display devices [5–7]. In OLEDs, semiconducting polymers and small organic molecules are commonly used as light-emitting materials [8–11]. Between cathode and anode, there are many organic sandwiched layers such as electron injection layer (EIL), electron transport layer (ETL), host layer (also known as an emissive layer), hole transport layer (HTL) and hole injection layer (HIL) and various blocking layers. The interface between electrodes and these organic layers greatly influences the efficiency of the OLED devices in terms of charge flow i.e. transport of electrons and holes between a cathode and an anode [12].
Fabrication of vertically aligned liquid crystal cell without using a conventional alignment layer
Published in Liquid Crystals, 2018
Masanobu Mizusaki, Yohei Nakanishi, Satoshi Enomoto
Liquid crystal displays (LCDs) are the most popular type of flat-panel displays and are used in television sets, notebook computers, smartphones, tablets, car navigations, digital signage and so forth because they have features such as high resolution, low power consumption and thinness. So far, the LCDs have usually used a twisted nematic (TN) mode [1,2], but the TN mode has disadvantages of narrow viewing angle and low contrast ratio. Therefore, other modes with wide viewing angle and high contrast ratio such as in-plane switching mode [3], fringe-field switching mode [4], multidomain vertical alignment (MVA) mode [5] and patterned vertical alignment (PVA) mode [6] have been developed. Among these modes, vertical alignment (VA) modes such as the MVA and PVA modes have a significantly high contrast ratio because liquid crystal (LC) molecules are vertically aligned, which induce little retardation. To achieve VA, VA layers, which are mainly made from polyimides having side chains, are usually prepared on a pair of substrate [7,8]. The preparation of the VA layers usually requires large amount of solvent, high–temperature operation for post-baking and cleaning process [9].
A switching threshold programmable high-linearity transimpedance amplifier for OLED pixel current mismatch measurement
Published in Journal of Information Display, 2020
Organic Light Emitting Diodes (OLED) display has become the most popular choice for modern mobile and large flat-panel display devices. One challenge of OLED display is to keep the brightness of pixels uniform across the panel. It is well known that this problem stems from the uncertainty of threshold voltage of mass-produced Thin Film Transistors (TFTs) that are used in an OLED driver circuit. To address this issue, many techniques have been reported to improve the uniformity by active compensation circuits [1,2]. Conceptually, the compensation process consists of (1) measuring the non-uniformity of the pixel current and (2) applying appropriate voltage or current adjustment in the OLED pixel driver. Therefore, to use this compensation technique, measuring the mismatch current in each OLED pixel is essential. Several current measurement circuits have been reported [3,4] but a current measurement circuit that is optimized for an OLED display system needs to be developed. Due to large number of pixels on the panel, OLED systems typically use multitude of transimpedance amplifiers (TIAs) to measure all pixel currents during a given time frame. When such TIAs are used to measure the current from a pixel using a current source as a driver circuit, the switching threshold voltage of the TIA input sets the source voltage of the current source. Therefore, if the TIA’s switching threshold voltage has uncertainty due to its own random device variation, it will add extra mismatch to the inherent pixel driver mismatch. To resolve this issue, this paper proposes a switching threshold programmable TIA topology for OLED pixel current measurement where the switching threshold can be digitally programmable.