Liquid Crystal Display
Liquid crystals were first discovered in the late 19th century by the Austrian botanist, Friedrich Reinitzer, and the term "liquid crystal" itself was coined shortly afterward by the German physicist, Otto Lehmann.

Liquid crystals are almost transparent substances, exhibiting the properties of both solid and liquid matter. Light passing through liquid crystals follows the alignment of the molecules that make them up - a property of solid matter. In the 1960s it was discovered that charging liquid crystals with electricity changed their molecular alignment, and consequently the way light passed through them; a property of liquids.

Since its advent in 1971 as a display medium, liquid crystal displays have moved into a variety of fields, including miniature televisions, digital still and video cameras and monitors and today many believe that the LCD is the most likely technology to replace the CRT monitor. The technology involved has been developed considerably since its inception, to the point where today's products no longer resemble the clumsy, monochrome devices of old. It has a head start over other flat-screen technologies and an apparently unassailable position in notebook and handheld PCs where it is available in two forms: high image quality thin-film transistor (TFT).


This is a basic measurement of how much information is on the screen. It is usually described as "some number" by "some number". The first "some number" is the horizontal (across the screen) resolution and the second "some number" is the vertical resolution (down the screen). The higher the number, the better, since that means there is more detail. Some examples:

NTSC VHS: 240 x 485

NTSC broadcast: 330 x 485

NTSC laserdisc: 425 x 485

ITU-R BT.601 (525/60): 720 x 485

Computer screen: 1280 x 1024

The maximum definition of a particular system is capable of reproducing. Resolution is measured in the number of discrete observable lines that can be reproduced on a system. The higher the resolution a system is capable of producing, the sharper the picture will appear. In TV, the resolution is measured in vertical and horizontal lines or the total number of observable black to white line transitions observable in the picture. The horizontal resolution is limited by the bandwidth of the television circuit, while vertical resolution is limited by the total number of TV scan lines. A high-resolution video camera or monitor can display 700 horizontal lines of resolution and 480 vertical lines or 700 x 480 resolution. While influenced by the number of pixels in an image (for high definition approximately 2,000 x 1,000, broadcast NTSC TV 720 x 487, broadcast PAL TV 720 x 576), note that the pixel numbers do not define ultimate resolution but merely the resolution of that part of the equipment. The quality of lenses, display tubes, film process and film scanners, etc., used to produce the image on the screen must all be taken into account. This is why a live broadcast of the Super Bowl looks better than a broadcast recorded and played off of VHS, while all are NTSC or PAL.

The amount of detail in the video image is measured along both the horizontal and vertical axes. In digital systems, the resolution is the number of pixels on a display surface. Computer CRT resolutions are usually given as the number of pixels per scan line and the number of scan lines, e.g. 640 x 480. Video resolution is measured in terms of lines of detail per horizontal scan line (horizontal resolution) and the total number of scan lines (vertical resolution).

The clarity or graininess of a video or computer image as measured by lines or pixels; the smallest resolvable detail in the image. The perceivable detail, or the ability of an image reproducing system to reproduce fine detail

Flat Panel Size CRT size Typical resolution
13" 15" 800x600
14" to 15" 17" 1024x768
17" 21" 1280x1024


Touch Screen - Environmental:

Operating: -10°C to 50°C
Storage: -40°C to 71°C

Functionality is not adversely affected within these operating guidelines.

Relative Humidity
Functional operating limits: 90% RH at max 35°C
Functional storage limits: 90% RH at max 35°C for 240 hrs, noncondensing

Thermal Cycling
The touchscreen shall be capable of functioning normally after the completion of fifty thermal cycles from room conditions to 70° C, back to room temperature; and then to -40° C and back to room temperature at a rate not to exceed 2º C per minute and with a one hour soak at each temperature extreme.

The touchscreen shall be capable of functioning normally after having its lower edge immersed in water containing 5% isopropyl alcohol to a height one third of the overall height of the touchscreen, for a period of six hours.

Water Spray
The touchscreen shall function normally and not be damaged by running water applied to the active area.

Chemical Resistance
The active area of the touchscreen is resistant to the following chemicals when exposed for a period of one hour at a temperature of 70°F (21°C):

Industrial Chemicals
Acetone, Methylene chloride, Methyl ethyl ketone, Isopropyl alcohol, Hexane, Turpentine, Mineral spirits, Unleaded Gasoline, Diesel Fuel, Motor Oil, Transmission Fluid, Antifreeze.

Food Service Chemicals
Ammonia-based glass cleaner, Laundry Detergents, Cleaners (Fantastic, Formula 409, Joy, etc.), Vinegar, Coffee, Tea, Grease, Cooking Oil, Salt.

The touchscreen shall be capable of operating at an altitude of 10,000 feet above sea level.

The touchscreen shall be capable of being stored without damage at an altitude of 50,000 feet above sea level.

The touchscreen shall not be damaged by being subjected to a vibration of 0.01 inches peak to peak excursion, at a frequency of 5 to 455 Hz, for a period of 15 minutes in each of three axes.

The touchscreen, in its standard shipping container, shall be capable of withstanding the drop test of Project 1A of the National Safe Transit Association Program Pre-shipment Test Procedures (10 drops from a height of 30 inches).

Touch Screen - Physical Damage Resistance:

Impact Strength
Spherical touchscreens, when supported on their four corners, shall be capable of withstanding a load of 20 pounds applied in the center of the active area through a stylus of one-inch diameter.

Distributed Load
Spherical touchscreens, when supported on their four corners, shall be capable of withstanding a load, evenly distributed over their surface, of 40 pounds.

Resistive-type Touch Screen:

How an AccuTouch Touchscreen Works: 
The Parts of a Touchscreen
The AccuTouch five-wire resistive touchscreen uses a glass panel with a uniform resistive coating. A thick polyester coversheet is tightly suspended over the top of a glass substrate, separated by small, transparent insulating dots. The coversheet has a hard, durable coating on the outer side and a conductive coating on the inner side.

What Happens During a Touch
When the screen is touched, it pushes the conductive coating on the coversheet against the coating on the glass, making electrical contact. The voltages produced are the analog representation of the position touched.

How the Touchscreen Controller Interprets Screen Measurement
When the controller is waiting for a touch, the resistive layer of the touchscreen is biased at +5V through four drivelines, and the cover sheet is grounded through a high resistance. When the touchscreen is not being touched, the voltage on the coversheet is zero. The voltage level of the coversheet is continuously converted by the analog-to-digital converter (ADC) and monitored by the microprocessor on the controller.

When the touchscreen is touched, the microprocessor detects the rise in the coversheet voltage and begins converting the coordinates as follows:

A) The microprocessor places the X drive voltage on the touchscreen by applying +5V to pins H and X and grounding pins Y and L. An analog voltage proportional to the X (horizontal) position of the touch appears on the cover sheet at pin S of the touchscreen connector. This voltage is digitized by the ADC and subjected to an averaging algorithm, then stored for transmission to the host.
B) Next, the microprocessor places the Y drive voltage on the touchscreen by applying +5V to pins H and Y and grounding pin X and L. An analog voltage proportional to the Y (vertical position of the touch) now appears on the coversheet at pin S of the touchscreen connector. This signal is converted and processed as described above for the X position

Why the Averaging Algorithm is Important
The averaging algorithm reduces noise resulting from contact bounce during the making and breaking contact with the touchscreen. Successive X and Y samples are tested to determine that their values differ by no more than a certain range. If one or more samples fall outside this range, the samples are discarded and the process is restarted. This is continued until several successive X samples (then Y samples) fall within the range. The average of these values is used as the X and Y coordinates respectively.

Once independent X and Y samples are obtained, coordinate pairs are sampled to eliminate the effects of noise. If a sample does not fall within an internal range, all X and Y coordinates are discarded and the independent X and Y sequence is restarted. Once acceptable coordinates have been obtained, an average coordinate is determined and communicated to the host processor.

Video Alignment
The X and Y values are similar to Cartesian coordinates, with X increasing from left to right and Y increasing from bottom to top. These absolute coordinates are arbitrary and unscaled, and will vary slightly from touchscreen to touchscreen. The AccuTouch controller can be calibrated for video alignment. This aligns the touchscreen coordinate system with the display image, reorients each axis, and scales the coordinates before they are transmitted to the host computer.

X- and Y-axis Measurements Originate from the Glass
AccuTouch five-wire technology utilizes the bottom glass substrate for both X- and Y-axis measurements. The flexible coversheet acts only as a voltage-measuring probe. This means that the touchscreen will continue working properly even with nonuniformity in the cover sheet's conductive coating. The result is an accurate, durable, and reliable touchscreen that offers drift free operation.

NEMA Rating:

Type 4 enclosures are intended for indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose directed water; and to be undamaged by the formation of ice on the enclosure.

NEMA 12:
Type 12 enclosures are intended for indoor use primarily to provide a degree of protection against dust, falling dirt, and dripping noncorrosive liquids.

Disk On Module: 

Products are fully IDE-Compatible Flash Disks that can be integrated onto any Single Board Computer. Which are designed to replace conventional low capacity disk drives or M-Systems SSD Disk-On-Chip Flash. These units are suitable for industrial applications and harsh environments since they are more durable than conventional hard disk drives.


PC/104 is simply a repackaged, modular version of the PC architecture intended for embedded applications where space, power consumption, and reliability are critical. These modules can serve as a mezzanine bus for an embedded SBC or it can become the entire computer and I/O system.
A PC/104 module is an Industry Standard Architecture (ISA) bus board reduced to 3.6 x 3.8-inch (90 x 96-mm) which is approximately the size of a 3.5-in diskette. The bus signal definitions and timing are the same. PC/104's P1 bus has 64 pins just like the PC-XT and is combined with 40-pins on P2 for full AT-compatibility.

VESA Mounting: 

 The VESA® FDMI™ Standard defines mounting interfaces, hole patterns and associated cable/power supply locations for LCD monitors, Panel PCs, and other flat panel devices.
VESA MIS-D, 100/75, C compliant monitors are equipped with either a 100 x 100 mm or 75 x 75 mm mounting hole pattern.

Rack Cabinet: 

A special type of cabinet in which equipment is installed. Most common are racks that will accept equipment that is 19 inches across with places for it to be screwed into the front. Many racks will have ground busses, power strips, and back doors. Some will provide air conditioning vents.

Rack Unit (EIA standard): 

 One rack unit or U is 1.75 inches in height. Most 19" rack equipment in broadcasting is specified to be mounted in increments of Us in height. For example, 2 Us would be 3.5 inches high.


ANSI standard defining the single-ended (unbalanced) interconnection scheme for serial data communications.


 A medium-range (typically up to 300 m/1000 ft or more) balanced serial data transmission standard. Data is sent using an ECL signal on two twisted pairs for bi-directional operation. Full specification includes 9-way D-type connectors and optional additional signal lines. RS-422 is widely used for control links around production and post areas for a range of equipment.


 A medium-range (typically up to 300 m/1000 ft or more) balanced serial data transmission standard. Data is sent using an ECL signal on two twisted pairs for bi-directional operation. Full specification includes 9-way D-type connectors and optional additional signal lines. RS-422 is widely used for control links around production and post areas for a range of equipment.

Tablet PC: 

A Tablet PC is a notebook or slate-shaped mobile computer. Its touchscreen or graphics tablet/screen hybrid technology allows the user to operate the computer with a stylus or digital pen, or a fingertip, instead of a keyboard or mouse.

The form factor offers a more mobile way to interact with a computer. Tablet PCs are often used where normal notebooks are impractical or unwieldy or do not provide the needed functionality.

Analog To Digital: 

An analog-to-digital converter (abbreviated ADC, A/D or A to D) is an electronic integrated circuit, which converts continuous signals to discrete digital numbers. The reverse operation is performed by a digital-to-analog converter (DAC).

Typically, an ADC is an electronic device that converts an input analog voltage (or current) to a digital number. The digital output may be using different coding schemes, such as binary, Gray code or two's complement binary. However, some non-electronic or only partially electronic devices, such as rotary encoders, can also be considered ADCs.

Uninterruptible Power Supply: 

An uninterruptible power supply (UPS), also known as an uninterruptible power source or a battery backup is a device which maintains a continuous supply
of electric power to connected equipment by supplying power from a separate source when utility power is not available. There are two distinct types of UPS:
off-line and line-interactive (also called online).

An off-line UPS remains idle until a power failure occurs, and then switches from utility power to its own power source, almost instantaneously. An on-line UPS
continuously powers the protected load from its reserves (usually lead-acid batteries), while simultaneously replenishing the reserves from the AC power.

The on-line type of UPS, in addition to providing protection against complete failure of the utility supply, provides protection against all common power problems,
and for this reason, it is also known as a power conditioner and a line conditioner.

While not limited to safeguarding any particular type of equipment, a UPS is typically used to protect computers, telecommunication equipment or other electrical
equipment where an unexpected power disruption could cause injuries, fatalities, serious business disruption or data loss. UPS units come in sizes ranging from
units that will back up a single computer without monitor (around 200 VA) to units that will power entire data centers or buildings (several megawatts). Larger
UPS units typically work in conjunction with generators.


international standard IEC 60529 classifies the level of protection provided against the intrusion of solid objects (including body parts like hands and fingers), dust, accidental contact, and water. It consists of the letters IP (for "international protection rating"[1], sometimes also interpreted as "ingress protection rating") followed by two digits and an optional letter.

The digits ('characteristic numerals') indicate conformity with the conditions summarized in the tables below. Where there is no protection rating with regard to one of the criteria, the digit is replaced with the letter X.

For example, an electrical socket rated IP22 is protected against the insertion of fingers and will not be damaged or 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. The standard aims to provide users with more detailed information than vague marketing terms such as "waterproof".


A 19-inch rack is a standardized (EIA 310-D, IEC 60297 and DIN 41494 SC48D) system for mounting various electronic modules in a "stack", or rack, 19 inches (482.6 mm) wide. Equipment designed to be placed in a rack is typically described as rack-mount, a rack-mounted system, a rack mount chassis, subrack, or occasionally, simply shelf. The slang expression for a subrack (generally 1U = 1.75 in = 44.45 mm height) is "pizza box" due to the similarity in size and shape, see also pizza box form factor. Most racks are sold in the 42U form: that is, a single rack capable of holding 42 1U pizza box servers.

Because of their origin as mounting systems for railroad signaling relays, they are still sometimes called relay racks, but the 19-inch rack format has remained a constant while the technology that is mounted within it has changed to completely different fields. This standard rack arrangement is widely used throughout the telecommunication, computing, audio, entertainment, and other industries, though the Western Electric 23-inch standard, with holes on 1-inch centers, prevails in telecommunications.

Typically, a piece of equipment being installed has a front panel height 1/32-inch (.03125") less than the allotted number of U's. Thus, a 1U rackmount computer is not 1.75-inches tall but is 1.71875-inches tall. 2U would be 3.46875-inches instead of 3.5-inches. This gap allows a bit of room above and below an installed piece of equipment so it may be removed without binding on the adjacent equipment.


Serial Advanced Technology Attachment (SATA, IPA: /'se?t?/ or /'sæt?/) is a computer bus primarily designed for the transfer of data between a computer and storage devices (like hard disk drives or optical drives).

The main benefits are thinner cables that let air cooling work more efficiently, faster transfers, the ability to remove or add devices while operating (hot swapping), and more reliable operation with tighter data integrity checks than the older Parallel ATA interface.

It was designed as a successor to the legacy Advanced Technology Attachment standard (ATA) and is expected to eventually replace the older technology (retroactively renamed Parallel ATA or PATA). Serial ATA adapters and devices communicate over a high-speed serial cable.


Universal Serial Bus (USB) is a serial bus standard to interface devices. A major component in the legacy-free PC, USB was designed to allow peripherals to be connected using a single standardized interface socket and to improve plug-and-play capabilities by allowing devices to be connected and disconnected without rebooting the computer (hot swapping). Other convenient features include providing power to low-consumption devices without the need for an external power supply and allowing many devices to be used without requiring manufacturer specific, individual device drivers to be installed.

USB is intended to help retire all legacy varieties of serial and parallel ports. USB can connect computer peripherals such as mouse devices, keyboards, PDAs, gamepads and joysticks, scanners, digital cameras, printers, personal media players, and flash drives. For many of those devices, USB has become the standard connection method. USB is also used extensively to connect non-networked printers; USB simplifies connecting several printers to one computer. USB was originally designed for personal computers, but it has become commonplace on other devices such as PDAs and video game consoles. In 2004, there were about 1 billion USB devices in the world.[1]

The design of USB is standardized by the USB Implementers Forum (USB-IF), an industry standards body incorporating leading companies from the computer and electronics industries. Notable members have included Apple Inc., Hewlett-Packard, NEC, Microsoft, Intel, and Agere.