Display Devices in Computer Graphics
Computer
Graphics generated pictures can be displayed on diversified display mediums
called video display devices. The primary output device in a graphics
system is a video monitor.
Basically, operation of the most video monitors is based on the cathode-ray tube
design.
some display devices are given below:
1) Cathode Ray
Tube (CRT)
2) Raster Scan
Display
3) Random Scan
Display
4) Colour CRT
Monitors
5) Colour
Generating Techniques
6) Direct View
Storage Tube (DVST)
7) Plasma Panel
Display
8) Liquid Crystal Display (LCD)
Cathode Ray Tube (CRT)
This is
a vacuum glass tube capable of converting a computer’s electrical signals into
variable images at high speed.
Raster Scan Display
In a raster-scan display, the electron beam is swept across the screen, one row at a
time from top to bottom. As the electron beam moves across each row, the beam
intensity is turned on and off to create a pattern of illuminated spots.
Random Scan Display
Random
scan monitors draw a picture one line at a time and for this reason, are also
referred to as vector displays (or stroke-writing or calligraphic
displays). The component lines of a picture and refreshed by a random-scan
system in any specified order.
Colour CRT Monitors
Color
tubes use three different phosphors which emit red, green, and blue light
respectively. They are packed together in stripes or clusters called “triads”
(as in shadow mask CRTs)
Colour Generating Techniques
A
color CRT monitor displays color pictures by using a combination of phosphors
that emit different colored light. By combining the emitted light a range of
colors can be generated.
Direct View Storage Tube (DVST)
The
DVST is similar to the CRT, except that it does not need to be refreshed
because the image in this is stored as a distribution of charges on the inside
surface of the screen.
Plasma Panel Display
It is a
device in which each pixel remains bright after it has been intensified. It is
very similar to DVST though its construction is very difficult. Plasma pan
display writes images on the display surface point by point, each point remains
bright after it has been intensified.
Liquid Crystal Display (LCD)
It is a
non-emissive device that produces a picture by passing polarized light through
a liquid–crystal material that can be aligned to either block or transmit the
light. LCD is given a name so, because the compound filled between the glass
plates is a crystalline arrangement of molecules, hence they flow like a
liquid.
