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Presented By: Gohel Jitendra T.(08EC24)
Modi Sagar M. ( 08EC42)
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MONITOR TECHNOLOGIES
CATHODE RAY TUBE (CRT)
LIQUID CRYSTAL DISPLAY (LCD)
PLASMA DISPLAY PANEL (PDP) ORGANIC LIGHT EMITTING DIODE
(OLED)
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RELATED TERMINOLOGIES
Pixel
Resolution
Display Size Viewing Angle
Brightness
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PIXEL :
PIXEL Picture Element
It is the smallest element forming an image.
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RESOLUTION :
No. of pixels per unit video display
Video Graphics Array (VGA):
720 pixels across by 400 pixels down intext mode.
640 pixels across by 480 pixels down in
graphics mode.
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DISPLAY SIZE :
Measured as distance
from one corner to the
diagonally oppositecorner.
Usually measured in
INCHES.
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VIEWING ANGLE :
It is angle from which
the screen can be seen from
side.
It is larger for CRT as
compared to LCD .
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BRIGHTNESS :
The amount of light emitted from the display
(more specifically known as luminance).
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CRT MONITOR
cathode-ray tube :
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CRT : PRINCIPLE :CRT display works on :
Electron emission .
Electrons are emitted from the Cathode tube. Phosphorescence .
It is the emission of visible light, when
electron beam strikes Phosphor material.
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CRT : WORKING :
1.Electron guns
2.Electron beams
3.Focusing coils
4.Deflection coils
5.Anode connection
6.Mask for separating beams for
RGB part of displayed image
7.Phosphor layer with RGB zones
8.Close-up of the phos-phor-coated
inner side of the screen
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CRT DISPLAY: ADVANTAGES :
Offers greater resolution .
Widest viewing angle
It is cheap as compared to LCD,PLASMAdisplays
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CRT DISPLAY:DISADVANTAGES :
Thickness is much larger
Cannot be used for smaller displays, like
watches. View area is less than the offered monitor
size.
It is more heavier.
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LCD
Liquid Crystal Display :
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LCD: WORKING :
When electric
current was passed
through the LCD panel,
the liquid crystals arealigned with the first
polarized glass
encountered and willmake a 90o twist when
approaching the other
polarized glass at the end.
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When this happens, the light from the
fluorescent backlight is able to pass through
and thus giving us a lighted pixel on the
monitor. The reason we see the colouredimages are due to the colour filter, light passes
through the filtered cells creates the colors.
When there is no electric current, the liquid
crystals will not twist and thus the light will
not pass through and a black pixel will be
shown.
LCD: WORKING :
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LCD: DISADVANTAGES:
The cost of a LCD is considerably at a high
price.
The LCD display will have slow response
times. The LCD display has a fixed resolution
display and cannot be changed.
The viewing angle of a LCD display is verylimited due to the Automatic pixel
tracking/phase controls.
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PLASMA TECHNOLOGY :
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DEFINATION:
A plasma
display panel (PDP) is
essentially a collectionof very small
uorescent-type
lamps, each a fewtenths of a millimeter
in size.
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The plasma display itself is a simpledevice consisting of two parallel glass plates
separated by a precise spacing of some tenths
of a millimeter and sealed around the edges.
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PLASMA DISPLAY : WORKING:
Address
electrode causes
gas to change to
plasma state.
The plasma emits
UV in discharge
region which
impinges on the
phosphor
Reaction
causes each
sub pixel to
produce red,
green, and blue
light.
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PLASMA DISPLAY : ADVANTAGES:
Supports large displays ,up to 103 inchesdiagonally.
Overall thickness of monitor is less than 10
cm. and can be installed on a wall. Faster response time,
Greater color spectrum,
Wider viewing angle
The plasma display units has a clearer image,
better colour quality and higher contrast ratio
than the CRT and LCD display units.
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PLASMA DISPLAY : DISADVANTAGES:
The plasma display unit has a very short lifespan, to be around 20,000 hours to 30,000 hours
Plasma display units are considerably more
expensive than CRT monitors. Plasma display units must be handled carefully
because they are a very fragile display unit.
Use more electricity, on average, than an LCD
TV. Generally do not come in smaller sizes than
37 inches
Heavier than LCD due to the requirement of a
glass screen to hold the gases
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ORGANIC LIGHT EMITTING
DIODES(OLEDs) :
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PRINCIPLE:
OLEDs are special
because they are made up
of organic polymermolecules (otherwise
known as plastic) allowing
light to emit when a
voltage is applied.
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OLEDs: WORKING :
When Voltage is
applied across the OLED
device allowing electrons
to travel from the cathodethrough the emissive layer
to make positively charged
electron holes in the
conductive layer where the
anode draws those
electrons.
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OLEDs: WORKING :
Quite simply, the anode is drawing
electrons through the emissive layer to provide
positive electron holes in the conductive layer.
Then the Positive holes and the Electronscollide and recombine which leads to a drop in
the electron energy level as visible light
radiation is emitted.
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OLEDs: ADVANTAGES :
Transparent
Flexible
Light-emitting, and quite bright (daylight
visible)
Large viewing angle Fast (< 1 microsecond
off-on-off)
Can be made large or smallA black screen with OLED screen technology
requires zero power input.
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PRINTERS :
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DEFINATION:
In computing, a
printer is a peripheral which
produces a hard copy(permanent readable text
and/or graphics) of
documents stored in
electronic form, usually on
physical print media such as
paper or transparencies.
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PRINTERS:
TYPES
Dot-matrix Printers
Inkjet printer Laser printer
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DOT-MATRIX PRINTERS :
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DOT-MATRIX PRINTERS: WORKING :
The printer head is made up of a row of pins -
usually 9 or 25 pins forming a vertical bar. To
form a letter, the pins are "fired" in quick
succession to press the ribbon against the paper.
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DOT-MATRIX PRINTERS:
DISADVANTAGES :
Print quality is poor and important
documents are not suitable to give tomanagers or customers
Very slow - slowest out of all three printers
Cannot produce color copies
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INKJET PRINTERS :
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INKJET PRINTERS :WORKING
The Inkjet Printer is a common type of printerwhich works by spraying a tiny drop of ink at
paper. The technology is probably best
explained by this animated picture.
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INKJET PRINTERS :WORKING
The printing works the same way as the dotmatrix print head above. The only difference is
that we are now using droplets of ink instead of
hammers. Inkjets work by having a print cartridge with a
series of tiny electrically-heated chambers
constructed by photolithography.
To produce an image, the printer runs a pulse of
current through the heating elements. A steam
explosion in the chamber forms a bubble, which
propels a droplet of ink onto the paper.
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INKJET PRINTERS: WORKING
When the bubble condenses, surplus ink is
sucked back up from the printing surface. The
ink's surface tension pumps another charge of
ink into the chamber through a narrow channelattached to an ink reservoir .
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LESER PRINTERS :
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LASER PRINTER: WORKING :
Images are produced on
a drum
A laser beam sets
electrical charge on dotson the drum
Magnetically charged
powder called toner flies to
the electrified dots on the
drum
The drum rolls the toner
on the paper
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LASER PRINTER: WORKING :
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The final stage is for the paper to pass
through very hot "rollers" which "melt" the ink
on to the paper Now lets look at how the laserwrites on the drum. Laser print demonstration
The heat "seals" the ink onto the paper instantly
making sure that you do not get smudging orcrinkling as you can with other printer types.
LASER PRINTER: WORKING :
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OTHER TYPES OF PRINTERS:
Soli ink use sticks of wax that are melted to
create the ink for printing. environmentally
friendly, no ozone production. Ink sticks last
approx. 3000 pages compared to average 1500
for laser printers.
Dye s blim tion:-High quality printer. Solid
dye contained on either a ribbon or a roll. Theroll is consecutive pages of cyan, magenta,
yellow and sometimes black. The dye diffusion
thermal process is known as D2T.
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