Folks today i am going to say
something about an output device called monitor. As maximum people know about monitors so i am
going to write few things about monitor much of the information you know but i
am going to say some few words hence please be with me.
Monitor is a primary output
device.
It displays all current process
application and data i.e. Running inside a computer system.
A standard monitor uses an analog vga
interface, which plugs into a tp15 vga connector to a mother board.
There are two types of monitor technology
available to the market.
CATHODE RAY TUBE (CRT MONITOR)
This monitor is fading in
popularity but still in widespread use with older computer systems. It is analog standard monitor a crt uses a
picture tube that was used in older tube based tv sets.
The narrow end of the picture tube contains an electron gun it emits 3
electron beams one each for red, green and blue light. The front end of the picture tube is coated
with phosphorous. When the elecron hit
the phosphorous coating it starts to glow.
Just before the phosphorous coating
a metal plate called a shadow mask uses one of the three technologies phosphor
triad, an aperture grill, a slotted mask.
Crt monitors are bulky, takes more
desk space, consumes more power and emits more heat. Crt monitors were available from 15 inch to
19 inch size. It uses vga connector to
attach with a cpu.
LCD AND LED SCREENS
The most popular monitor in todays
market is led monitor surpassed lcd monitors.
Because it gives better color quality, wide viewing angle and consumes
less power. It uses liquid crystal cells
to polarize the light. Lcd uses fluorescent
lamp and led monitor uses led lamp for back lighting. This display uses an array of transistors to
control each cell variation are the colour bit response time and the refresh
rate.
This monitor comes with two types
of transistor technology (1) passive matrix (2) active matrix.
Now i will discuss about passive
matrix so lets be.
PASSIVE MATRIX
A passive matrix display does not
have a dedicated transistor for each pixel or sub pixel, bit instead of a
matrix of conductive traces. In
simplified terms for a single pixel, when the display is instructed to change the crystal line alignment for a
particular pixel and sends a signal
accross the x and y coordinate traces that intersect at that pixel, thus
turning it on. A 1366 * 768 resolution monitor
contains 1366 transistors at that horizontal edge and 768 in vertical edge. The
viewing uncle is a most unconsiderable issue of a passive matrix display. The pitchure quality is muddy because the
conductive traces sometimes affects the neighbouring pixels of a target pixel.
The one advangage of passive matrix is it consumes less power comparing to
active matrix display.
DUAL SCAN DISPLAY
A dual scan is a variation of the passive metric display. The classic passive matrix screen is split in
half to implement a dual scan display.
Each half of the display is refreshed separatly leading to increased
quality. Although dual scan improves the
quality of refresh rate but it cannot rival the quality produced by active
matrix.
ACTIVE MATRIX
This screen is made of several
independent lcd or led pixels. A
transistor at each pixel location, when switched among various levels activates
two opposing electrodes that align the pixels crystal two opposing electrodes
that align the pixels crystals and alter the passage of light at that location
two produce millions of colour shades.
This type of display is very
crisp and easy to look at from any angle.
It doesn’t require a scan refreshing to maintain an image. Because transistors conduct current only in
one direction and the pixels acts like a capacitor by holding its charge until
it is refreshed.
Higher refresh rate results in better video a
gaining performance not for still image.
The major disadvantage of active matrix screeen but it reuqir3es more
power to operate all transistors. Even
if the backlight is turned of the screen can still consume power at an alarming
rate. Another problem with active matrix
is light bleed.
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