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12
Glossary
AMTFT—
Active Matrix Thin Film Transistor. This is the type of liquid crystal display panel used in essentially all
computer flat panel displays today.
Calibrate—
For touchscreens, “calibrate” is the common term for the process that is really “video alignment.”
A touchscreen and its controller have a coordinate system that are usually not identical to the coordinate system of
the video display of the host computer. By displaying reference points on the touch monitor (through the calibration
program) and touching those reference points, the touch monitor coordinate system is scaled to that of the computer.
Color temperature—
Color temperature is a simplified way to characterize the spectral properties of a light source,
and is the temperature you would heat a theoretical “black body” source to radiate light of the same visual color.
For example, “low” color temperature, like 3200°K, implies warmer (more yellow/red) light, while “high” color tem-
perature, like 9300°K, implies a cooler (more blue) light. Daylight has the 3200°K temperature mentioned near
dawn and evening, and a higher one during the day. The standard unit for color temperature is the Kelvin (k).
Contrast Ratio—
The ratio of the luminance of the display of a full white image to a full black image. This parameter
is useful in determining the relative sharpness of two displays—a higher contrast ratio usually implies a sharper
image, especially when test is displayed.
Controller—
Touchscreen controller. The electronics that actually process the touch on the touchscreen and
sends out a digital representation of that touch to the host computer.
Emulation—
As used in display technology, emulation mode means an image displayed at a non-native resolution.
For your Aspen touch monitor and other 17" monitors, the common emulation modes are 800x600 and 640x480.
In emulation modes, a monitor cannot perfectly display the image sent from the computer when the monitor pixel
to image pixel ratio is not an integral multiple.
FRC—
Frame Rate Control. A method of dithering the video image to produce additional color depth. In this monitor,
as with most 17" monitors, it effectively extends the color depth from 6-bit resolution to 8-bit resolution.
Hub or USB hub—
An electronic circuit that combines several USB signals into one.
Illuminance—
The measure of how much luminous flux per unit area that impinges on a particular surface, or
how bright a point source of light appears to the eye. It is measured in foot-candles or in lux.
Kelvin—
The scale of temperature measurement that begins at absolute zero. The increment of temperature that
one Kelvin represents is the same as that of the Celsius scale, but the scale starts at -273.16°C. Thus 293°K is
about 20°C or 68°F.
Keyboard emulation—
Produces the same output as a keyboard, or a “keyboard wedge” magnetic stripe reader.
Keyboard wedge—
An MSR unit that connects to a computer keyboard port with a cable that also connects the
standard keyboard, thus a keyboard wedge.
LCD—
Liquid Crystal Display. The most common technology used in flat computer displays today. “Liquid crystal”
molecules (a very complex chemical engineered for this function) sandwiched between a combination of flat glass
color filters and polarizers, pass or block light in response to electrical signals applied by the display electronics.
The result is a very sharp, bright display that is very thin, and uses little power, compared with a CRT, or tube-type
monitor.
Lux—
The standard unit for illuminance is lux (lx) which is lumens per square meter (lm/m2). 1 lux = 10.764 foot-
candle. Common room lighting is 100-1000 lux.
MSR—
Magnetic Stripe Reader. A device that reads information encoded in the magnetic stripes on the back of a
credit card, etc. The process is essentially identical to the operation of a cassette tape player.
