TECHNICAL GLOSSARY
ACTIVE AREA: Physical glass area occupied by Liquid Crystal. AA= n x Dot Pitch + Dot Size, where n is the number of pixel on any axis.
CANDELA:The candela (/kænˈdɛlə/ or /kænˈdiːlə/; symbol: cd) is the unit of luminous intensity in the International System of Units (SI). It measures luminous power per unit solid angle emitted by a light source in a particular direction. Luminous intensity is analogous to radiant intensity, but instead of simply adding up the contributions of every wavelength of light in the source's spectrum, the contribution of each wavelength is weighted by the luminosity function, the model of the sensitivity of the human eye to different wavelengths, standardized by the CIE and ISO. A common wax candle emits light with a luminous intensity of roughly one candela. If emission in some directions is blocked by an opaque barrier, the emission would still be approximately one candela in the directions that are not obscured.
COVER LENS: LCD's and TFT's are as a standalone product arguably fragile. Industrial applications will often deploy a protective layer on the outer surface, attached to the display. This is known as a cover lens. Touch sensors also integrate cover lenses to ruggedise the product, and protect it from damage and vandalism. Cover lenses can be manufactured from glass, polycarbonate or PMMA (Polymethyl Methacrylate).
CRT:A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen.The images may represent electrical waveforms (oscilloscope), pictures (television set, computer monitor), radar targets, or other phenomena. A CRT on a television set is commonly called a picture tube. The term cathode ray was used to describe electron beams when they were first discovered, before it was understood that what was emitted from the cathode was a beam of electrons.
In CRT computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster. In color devices, an image is produced by controlling the intensity of each of three electron beams, one for each additive primary color (red, green, and blue) with a video signal as a reference. In modern CRT monitors and televisions the beams are bent by magnetic deflection, using a deflection yoke.
EDID: Extended Display Identification Data (EDID) and Enhanced EDID (E-EDID) are metadata formats for display devices to describe their capabilities to a video source (e.g., graphics card or set-top box). The data format is defined by a standard published by the Video Electronics Standards Association (VESA). The EDID data structure includes manufacturer name and serial number, product type, phosphor or filter type (as chromaticity data), timings supported by the display, display size, luminance data and (for digital displays only) pixel mapping data. DisplayID is a VESA standard targeted to replace EDID and E-EDID extensions with a uniform format suited for both PC monitor and consumer electronics devices.
ESD: Electrostatic discharge (ESD) is a sudden and momentary flow of electric current between two electrically charged objects caused by contact, an electrical short or dielectric breakdown. A buildup of static electricity can be caused by tribocharging or by electrostatic induction. The ESD occurs when differently-charged objects are brought close together or when the dielectric between them breaks down, often creating a visible spark.
This can cause harmful effects of importance in industry, including explosions in gas, fuel vapor and coal dust, as well as failure of solid state electronics components such as integrated circuits. These can suffer permanent damage when subjected to high voltages. Electronics manufacturers therefore establish electrostatic protective areas free of static, using measures to prevent charging, such as avoiding highly charging materials and measures to remove static such as grounding human workers, providing antistatic devices, and controlling humidity.
ESD simulators may be used to test electronic devices, for example with a human body model or a charged device model.
GORILLA GLASS: Gorilla Glass is a brand of chemically strengthened glass developed and manufactured by Corning, now in its eighth generation. Designed to be thin, light and damage-resistant, the glass gains its surface strength, ability to contain flaws, and crack-resistance by being immersed in a hot, potassium-salt, ion-exchange bath.
The alkali-aluminosilicate sheet glass is used primarily as cover glass for portable electronic devices, including mobile phones, smartwatches, portable media players, portable computer displays, and television screens.
HDMI : High-Definition Multimedia Interface (HDMI) is a proprietary audio/video interface for transmitting uncompressed video data and compressed or uncompressed digital audio data from an HDMI-compliant source device, such as a display controller, to a compatible computer monitor, video projector, digital television, or digital audio device. HDMI is a digital replacement for analog video standards.
HMI Design: HMI stands for Human Machine Interface. Generally, it refers to a screen or dashboard that communicates information, data and metrics using graphics or visual representations of numbers. The screen is controlled by an operator who monitors and controls equipment and processes in factories and plants.
EOL :''End of Life'' describes the scenario whereby a component or module design ceases to be supported and manufactured, often forcing the user to make a last time buy purchase.
IP RATING: The IP code or ingress protection code indicates how well a device is protected against water and dust. It is defined by the International Electrotechnical Commission (IEC) under the international standard IEC 60529 which classifies and provides a guideline to the degree of protection provided by mechanical casings and electrical enclosures against intrusion, dust, accidental contact, and water. It is published in the European Union by the European Committee for Electrotechnical Standardization (CENELEC) as EN 60529.
The standard aims to provide users more detailed information than vague marketing terms such as waterproof. For example, a cellular phone rated at IP67 is "dust resistant" and can be "immersed in 1 meter of freshwater for up to 30 minutes". Similarly, an electrical socket rated IP22 is protected against insertion of fingers and will not become unsafe during a specified test in which it is exposed to vertically or nearly vertically dripping water. IP22 or IP2X are typical minimum requirements for the design of electrical accessories for indoor use.
IPS TFT: IPS (in-plane switching) is a screen technology for liquid-crystal displays (LCDs). In IPS, a layer of liquid crystals is sandwiched between two glass surfaces. The liquid crystal molecules are aligned parallel to those surfaces in predetermined directions (in-plane). The molecules are reoriented by an applied electric field, whilst remaining essentially parallel to the surfaces to produce an image. It was designed to solve the strong viewing angle dependence and low-quality color reproduction of the twisted nematic field effect (TN) matrix LCDs prevalent in the late 1980s.
LVDS: Low-voltage differential signaling (LVDS), also known as TIA/EIA-644, is a technical standard that specifies electrical characteristics of a differential, serial signaling standard. LVDS operates at low power and can run at very high speeds using inexpensive twisted-pair copper cables.
MCU/CPU Display Interfaces: include two types, 6800 and 8080. 8080 is more common than 6800. Typically the MCU interface consists of 4/8/9/16 bits data (like DB0, DB1, , , DB7; Note: 8bits is the most popular bits width), CS (chip select), RS (data register or instruction register select), RD (read enable), WR (write enable).
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PROs: Simple interfacing.
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CONs: Requirement for RAM to buffer imagery, Speed is limited.
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Used in Mono character, graphic, small TFT (smaller than 3.5”)
MIPI (Mobile Industry Processor Interface): MIPI is a standardized interface for connecting peripherals and sensors to the embedded processor within a mobile device. This interface is designed to be low-power, high-speed, and flexible, making it well-suited for use in mobile devices such as smartphones and tablets.
There are several different types of MIPI interfaces, including MIPI-CSI2, MIPI D-PHY, MIPI C-PHY, MIPI M-PHY, and MIPI I3C. Each of these interfaces serves a specific purpose and has different characteristics in terms of data rate, power consumption, and physical layer implementation.
Increasingly SOM/SBC design integrates 4 Lane MIPI, to cope with higher resolution TFT.
MOHS Hardness Scale: The Mohs scale of mineral hardness is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of minerals through the ability of harder material to scratch softer material. The samples of matter used by Mohs are all different minerals. Minerals are chemically pure solids found in nature. Rocks are made up of one or more minerals. As the hardest known naturally occurring substance when the scale was designed, diamonds are at the top of the scale.
MONO LCD: A liquid-crystal display (LCD) is a flat-panel display or other electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers. Liquid crystals do not emit light directly but instead use a backlight or reflector to produce images in color or monochrome. LCDs are available to display arbitrary images (as in a general-purpose computer display) or fixed images with low information content, which can be displayed or hidden: preset words, digits, and seven-segment displays (as in a digital clock) are all examples of devices with these displays. They use the same basic technology, except that arbitrary images are made from a matrix of small pixels, while other displays have larger elements. LCDs can either be normally on (positive) or off (negative), depending on the polarizer arrangement. For example, a character positive LCD with a backlight will have black lettering on a background that is the color of the backlight, and a character negative LCD will have a black background with the letters being of the same color as the backlight. Optical filters are added to white on blue LCDs to give them their characteristic appearance.
MOTHER-GLASS : A substrate that serves as a foundation for display is essential to manufacture a display. ‘Mother Glass’ refers to a large piece of glass that lays the groundwork for display production. The mother glass is classified into different generations depending on their sizes.
Panels that constitute either OLEDs or LCDs are produced through several processes on top of a large block of mother glass. These panels that we are familiar with are not produced respectively, but once fabricated through manufacturing processes, and mother glasses are cut into smaller display sizes.
MOQ : Minimum Order Quantity. This terms refers to the minimum quantity of a certain product that can be ordered at one time in production. Note that it is often possible to schedule an MOQ, so 1K unit MOQ becomes 1K units taken periodically over 24 months.
OPTICAL BONDING: Optical bonding is the use of an optical-grade adhesive to glue a glass to the top surface of a display. The main goal of optical bonding is to improve the display performance under outdoor environments. This method eliminates the air gap between the cover glass and the display. Moreover, anti-reflective coating is often used in optical bonding glass. The real problem for display readability in outdoor environments is not the display's brightness but its contrast. Contrast means the ratio of the white level to the black level; in other words, the contrast ratio of display means the difference of light intensity between the brightest white pixel and the darkest black pixel. The main purpose of optical bonding is to increase the display's contrast ratio by reducing the amount of reflected ambient light.
PCT: A capacitive touchscreen panel consists of an insulator, such as glass, coated with a transparent conductor, such as indium tin oxide (ITO).As the human body is also an electrical conductor, touching the surface of the screen results in a distortion of the screen's electrostatic field, measurable as a change in capacitance. Different technologies may be used to determine the location of the touch. The location is then sent to the controller for processing. Some touchscreens use silver instead of ITO, as ITO causes several environmental problems due to the use of indium. The controller is typically a complementary metal–oxide–semiconductor (CMOS) application-specific integrated circuit (ASIC) chip, which in turn usually sends the signals to a CMOS digital signal processor (DSP) for processing.
PWM BACKLIGHT CONTROL: Pulse Width Modulation (PWM) is one method of reducing the perceived luminance in displays, which it achieves by cycling the backlight on and off very rapidly, at a frequency you can’t necessary detect with the naked eye, but which could lead to eye issues, headaches etc. This method generally means that at 100% brightness a constant voltage is applied to the backlight and it is continuously lit. As you lower the brightness control the perceived luminance for the user reduces due to a number of possible controlling factors:
RACK UNIT: A rack unit (abbreviated U or RU) is a unit of measure defined as 1+3⁄4 inches (44.45 mm).It is most frequently used as a measurement of the overall height of 19-inch and 23-inch rack frames, as well as the height of equipment that mounts in these frames, whereby the height of the frame or equipment is expressed as multiples of rack units. For example, a typical full-size rack cage is 42U high, while equipment is typically 1U, 2U, 3U, or 4U high. The 19-inch rack format with rack-units of 1.75 inches (44.45 mm) was established as a standard by AT&T around 1922 in order to reduce the space required for repeater and termination equipment in a telephone company central.
RGB: The RGB interface is a special parallel interface that transmits up to 8-bits of red, green and blue data to each pixel. The number of bits transmitted per clock cycle is dependent on the setup and programming of the display. It can vary from 16 to 18 or 24 data pins that are used for each of the RGB signals.
TFT: A thin-film-transistor liquid-crystal display (TFT LCD) is a variant of a liquid-crystal display that uses thin-film-transistor technology[1] to improve image qualities such as addressability and contrast. A TFT LCD is an active matrix LCD, in contrast to passive matrix LCDs or simple, direct-driven (i.e. with segments directly connected to electronics outside the LCD) LCDs with a few segments.
TN TFT: The twisted nematic display is one of the oldest and frequently cheapest kind of LCD display technologies available. TN displays benefit from fast pixel response times and less smearing than other LCD display technology, but suffer from poor color reproduction and limited viewing angles, especially in the vertical direction. Colors will shift, potentially to the point of completely inverting, when viewed at an angle that is not perpendicular to the display. TN is still utilised in modern display applications where low cost is key to design and production.
TRANSFLECTIVE TFT: A transflective liquid-crystal display is a liquid-crystal display (LCD) with an optical layer that reflects and transmits light (transflective is a portmanteau of transmissive and reflective). Under bright illumination (e.g. when exposed to daylight) the display acts mainly as a reflective display with the contrast being constant with illuminance. However, under dim and dark ambient situations the light from a backlight is transmitted through the transflective layer to provide light for the display. The transflective layer is called a transflector. It is typically made from a sheet polymer. It is similar to a one-way mirror but is not specular. Transflective displays are considered niche, and are often more expensive than Transmissive, they are also often selected for low power and sunlight readability. Negative aspects of their use include Contrast Ratio loss in bright sunlight, the colours tend to wash out.
USB: Universal Serial Bus (USB) is an industry standard that specifies the physical interfaces and protocols for connecting, data transferring and powering of hosts, such as personal computers, peripherals, e.g. keyboards and mobile devices, and intermediate hubs. USB was designed to standardize the connection of peripherals to computers, replacing various interfaces such as serial ports, parallel ports, game ports, and ADB ports. It has become commonplace on a wide range of devices, such as keyboards, mice, cameras, printers, scanners, flash drives, smartphones, game consoles, and power banks.