Display Device & Printer

8/8/2019 Display Device & Printer

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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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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.



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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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Display Device & Printer