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Monitors / Displays
CASANOVA
COLLECTION
- OFFICIAL SCIENCE & TECHNOLOGY PROVIDER PARTNER
  
World Industry Standards
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Bandwidth |
This is a qualitative term used to describe the monitor's video
amplifier potential performance. The higher the pixel rate (or
format number), the higher the bandwidth required of the video
amplifier. |
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Barrel |
An outward bowing of the picture.
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Brightness |
Light output measured at the faceplate of the CRT; typically
measured in foot lamberts (Fl). A minimum brightness level of 20Fl
when viewing at full-page size is considered acceptable. |
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Color Balance |
The ability of the monitor to show and maintain the same color when
switching or varying the intensity of the screen. |
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Color Display |
Color units are defined as displays/tubes which show 3 or more
colors. Often, we hear the terms multi-color and the ubiquitous full
color. With three primary colors and a large number of shades (gray
levels) for each primary color, a display can represent full color
video or computer graphic images. In the world of television and
computers, it has now come to mean 16.777 million colors. The number
of acceptable color shades or gray level is 256. This means 256
shades of red, 256 shades of blue, and 256 shades of green to give
16,777,216 colors (256 x 256 x 256 = 16,777,216). This has become
the de facto standard for what can be called full color displays.
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CGA |
Color Graphics Adapter.
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CRT |
This abbreviation stands for Cathode Ray Tube, also known as picture
tube or screen. The picture tube in a home TV is also a CRT.
|
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Diagonal Linear Measurement |
"Official" screen size is the diagonal measurement of the CRT before
it's mounted in the monitor cabinet. Some monitor CRT category sizes
are 14", 15", 17", 19", and 21."
|
|
Dot Pitch |
The distance between the one phosphor dot and the nearest dot of the
same color in the line above or below. |
| DSTN |
Abbreviation
of Dual-scan STN, an enhanced STN passive matrix LCD display. The
screen is divided into halves, and each half is scanned
simultaneously, thereby doubling the number of lines refreshed per
second and providing a sharper appearance. DSTN is widely used on
laptops.. |
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EGA |
Extended Graphics Adapter.
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EVGA |
Extended Video Graphics Array.
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Flicker |
'Flicker' refers to 'screen flicker'. Screen flicker results
from a variety of factors, the most important of which is the
monitor's refresh rate. The refresh rate being the speed that
it takes to redraw the entire screen. If the refresh rate is
too slow, the screen will appear to glimmer. Screen Static is
the noise produced in a radio or television receiver by electrical
disturbances. In a picture tube display, flicker refers to the
lit condition of the display caused by mismatch of phosphor and
vertical refresh when the phosphor begins to decay prior to being
refreshed giving the display the appearance of "flashing." |
|
Horizontal Frequency |
This indicates how long it takes to scan each of the horizontal
lines that make up the display. The unit of measurement is kilohertz
(KHz). It is directly related to the number of lines and the
vertical refresh frequency so that the higher the vertical refresh
or the number of lines, the higher the horizontal frequency
required. |
|
HPA
|
Short for High-Performance Addressing, a
Passive-Matrix Display technology that provides better response
rates and contrast than conventional LCD displays. Although HPA
displays aren't quite as crisp or fast as Active-Matrix (TFT)
displays, they're considerably less expensive to produce.
Consequently, HPA is being used by a number of computer
manufacturers for their entry level or value notebook computers. |
|
Interlaced |
Method of significantly increasing data densities at conventional
horizontal scan rates. Half the image is refreshed (every other scan
line) to produce a field. Two fields are refreshed at rates of 87 Hz
forming one 43.5 Hz frame. Causes flicker on the display.
|
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LCD |
Abbreviation of Liquid Crystal Display, a
type of display used in digital watches and many portable computers.
LCD displays utilize two sheets of polarizing material with a liquid
crystal solution between them. An electric current passed through
the liquid causes the crystals to align so that light cannot pass
through them. Each crystal, therefore, is like a shutter, either
allowing light to pass through or blocking the light. |
|
Maximum Viewing Area |
The actual maximum viewing area is dependent upon the size of the
plastic or bezel around the CRT. Typically, the maximum possible for
a 17" monitor is actually 15.75" plus or minus 1/2" (+/- 0.25" at
the ends of the diagonal measurement). |
|
Parallelogram |
A deviation of the sides from the true vertical.
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Persistence |
Phosphor characteristic consisting of the ability to
emit light after excitation current of electron beam is
removed |
|
Phosphor |
Chemical compound that emits light while being excited by electrons. |
|
Pincushion |
An inward bowing of the video image. All monitors experience slight
amount of pincushion distortion. The manufacturer has a guideline on
what the specification is for each model. The pincushion changes per
resolution and also according to the size of the image. Pincushion
is similar to bowing or barrel distortion. |
|
Pixel |
Abbreviation for "picture element." These are the building blocks of
electronic images. Pixels are the smallest part of an image the
computer's monitor or printer can display or control.
The concept of a pixel in a CRT color screen can be explained with
the help of the diagram shown below, which illustrates an exploded
view of the arrangement of color phosphor dots into "triads" on a
typical shadow mask color CRT. This diagram clearly shows how a
pixel is formed from a number of phosphor dots and the relationship
among addressable pixel size. A pixel is not a triad in a CRT.
Each triad is composed of a red, green, and blue phosphor dot. The
dot pitch is defined at the center-to-center distance between
adjacent green phosphor dots; this is resolution parameter. Because
the shadow mask is made using photolithography, this distance can be
accurately controlled. Each hole in the shadow mask exposes one
triad. When all three electron beams strike all three dots in a
triad with equal intensity, the pixel will be white. The other
colors of the spectrum can be obtained by varying the intensity of
each of the electron beam. To enhance contrast, the color phosphor
dots are usually surrounded by a black material. |
|
Refresh Rates |
An ergonomic issue that is directly related to long term ease of
use. A higher refresh rate translates to a more "flicker" free
display. Bandwidth, horizontal, and vertical scanning rates depict a
monitor's ability to provide a higher resolution and refresh rate.
|
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Resolution |
Resolution refers to the number of pixels or dots per linear distance, dots per inch
(DPI). There is one parameter, which is most helpful in defining
resolution: pixel density, or the number of pixels per linear
distance (pixels per inch or pixels per centimeter). Simply put,
this parameter tells us how close together the pixels actually are. The pixel or dot pitch is a resolution parameter. The dot pitch is
usually given in millimeters in the specifications of a CRT color
tube. Unfortunately, the
pixel density and the
dot density are the
true measure of resolution in a CRT. However, these are rarely
specified in advertising.
Resolution is related to the sharpness and
clarity of an image. The term is most often used to describe
monitors, printers, and bit-mapped graphic images. In the case
of dot-matrix and laser printers, the resolution indicates the
number of dots per inch. For example, a 300-dpi (dots per
inch) printer is one that is capable of printing 300 distinct dots
in a line 1 inch long. This means it can print 90,000 dots per
square inch.
For graphics monitors, the screen resolution signifies the number of
dots (pixels) on the entire screen. For example, a 640-by-480
pixel screen is capable of displaying 640 distinct dots on each of
480 lines, or about 300,000 pixels. This translates into
different dpi measurements depending on the size of the screen.
For example, a 15-inch VGA monitor (640x480) displays about 50 dots
per inch.
SXGA: A display with 1280 x 1024 pixel
resolution.
XGA: A display with 1024 x 768 pixel resolution.
SVGA: A display with 800 x 600 pixel resolution.
VGA: A display with 640 x 480 pixel resolution.
Printers, monitors, scanners, and other I/O devices are often
classified as high resolution, medium resolution, or low resolution.
The actual resolution ranges for each of these grades is constantly
shifting as the technology improves.
|
|
TFT |
Abbreviation of Thin Film Transistor, a type
of LCD flat-panel display screen, in which each pixel is controlled
by from one to four transistors. The TFT technology provides the
best resolution of all the flat-panel techniques, but it is also the
most expensive. TFT screens are sometimes called Active-Matrix LCDs.
|
|
Tilt |
The angle of the CRT with respect to the horizontal mounting bracket
of the chassis. Tilt can vary depending on the monitors' orientation
to the Earth's magnetic poles. Monitor manufacturers orient and
align their products in the Eastern direction. When the monitor is
facing a north/south direction, there may be a slight rotation of
the image. |
|
Vertical Frequency |
This indicates how many times per second the monitor can draw all
the lines on an entire screen. A higher vertical frequency or
refresh rate will produce less flicker. |
|
VGA |
Video Graphics Array. |
|
VIDEO RAM
|
Video RAM Required for Different Resolutions
Resolution |
256
colors
(8-bit) |
65,000
colors
(16-bit) |
16.7
million colors
(24-bit, true color) |
|
640x480 |
512K |
1 MB |
1 MB |
|
800x600 |
512K |
1 MB |
2 MB |
|
1,024x768 |
1 MB |
2 MB |
4 MB |
|
1,152x1,024 |
2 MB |
2 MB |
4 MB |
|
1,280x1,024 |
2 MB |
4 MB |
4 MB |
|
1,600x1,200 |
2 MB |
4 MB |
6 MB |
|
|
XGA |
Extended Graphics Array,
a high-resolution graphics standard introduced by IBM in 1990. XGA
was designed to replace the older 8514/A video standard. It provides
the same resolutions (640 by 480 or 1024 by 768 pixels), but
supports more simultaneous color (65 thousand compared to 8514/A's
256 colors). In addition, XGA allows monitors to be non-interlaced. |
MONITOR SAFETY/REGULATORY
TERMS
|
DDC1 |
A uni-directional data channel from the display to the host,
continuously transmitting Extended Display Identification (EDID)
information. |
|
DDC2 |
A bi-directional data channel based on the I2C protocol. The host
can request EDID (Extended Display Identification) or VDIF
information over the DDC2 channel. In addition, the DDC2 channel can
act as a transparent channel for ACCESS.bus communication.
|
|
DDC1/2B |
Displays capable of continuously transmitting its extended
identification (EDID) using DDC1 communication channel. In addition,
the display can respond to a request for EDID, or complete VDIF, to
be transmitted using DDC2 Level B commands. If a DDC2 capable host
is detected by a DDC2 capable display, the display will switch to
DDC2 communications. The display is incapable of switching from DDC2
to DDC1 unless power is removed. |
|
Extended Display Identification (EDID) |
Data structure containing the display identity and the basic display
specifications. |
|
MPR II |
The Swedish National Board for Measurement and Testing (SWEDAC)
requires that products sold in Sweden comply with a set of safety
standards known as MPR II, that covers the levels of magnetic and
electrical fields in both the VLF and ELF ranges. It is worth noting
that there are no scientific studies that conclude that measurements
above MPR II levels are hazardous. To measure emissions, a
sophisticated testing area that screens out background radiation
needs to be in place. Since distance to the CRT and orientation of
the measuring device effects measurement, precise placement of the
measuring device is essential and difficult to repeat. For the MPR
standards, 48 different locations around the monitor
need to be measured. In addition, the actual image
displayed can have an impact on emissions so that a
given set of measurements may not predict the emissions
a user would actually encounter |
|
NUTEK |
National Board for Industrial and Technical Development in Sweden.
NUTEK is a government body that works toward better energy
conservation, among other things by stimulating companies to develop
energy-efficient products, such as refrigerators, cooking stoves,
and office equipment. |
|
SEMKO AB |
Performs international certification for electrical products. This
company certifies company quality assurance systems and includes
environmental certification. Competence in measuring methods offered
by SEMKO contributes to the TCO '95 certification requirements, and
the company carries out post-certification checks, on behalf of TCO,
on TCO-labeled displays. |
|
TCO '92 |
TCO '92 only covers displays and their characteristics regarding
electrical and magnetic fields, energy efficiency and electrical and
fire safety. The display must meet the following requirements: it
must follow the TCO guidelines for low radiation; the display must
be equipped with an automatic power-down function; the supplier must
include an energy declaration; the display must meet the European
fire and electrical safety requirements; the supplier shall have
concluded a certification agreement with the TCO. |
|
TCO '95 |
TCO '95 includes the complete personal computer, i.e. the display,
system unit and keyboard, and touches on ergonomic qualities,
emissions (electrical and magnetic fields, noise and heat), energy
efficiency, and ecology (with demands for environmental adaptation
for both the product and the production processes at the
manufacturing plant). Note: the term "personal computer" includes
workstations, desktop and desk side computers, servers and Macintosh
computers. |
|
VESA |
The prominent standards organization for graphics subsystems. VESA
has developed a communication channel between the host computer and
the display. It offers basis configuration as well as providing a
standard way of communicating advanced functionality. |
|
VDIF |
Data structure containing full display specifications |
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