MONITORMONITOR

Monitor is the commonly used output Monitor is the commonly used output devicedevice

It is a softcopy deviceIt is a softcopy device It is similar to the commonly used It is similar to the commonly used

Television except some circuits insideTelevision except some circuits inside Monitor is the basic equipment for the Monitor is the basic equipment for the

computercomputer The user of a computer will see his The user of a computer will see his

results through this deviceresults through this device

ClassificationClassification

Based on input signal used we can Based on input signal used we can classify in to two classify in to two

DigitalDigital These types of monitors uses digital These types of monitors uses digital

signalssignals It does not support more colours as It does not support more colours as

required,because of the complication required,because of the complication of the circuitry of the circuitry

Analog monitorAnalog monitor Analog monitors uses analog signalsAnalog monitors uses analog signals Now we are using analog monitorsNow we are using analog monitors We can produce unlimited number of We can produce unlimited number of

colours by using analog signalscolours by using analog signals

Important parts of a Important parts of a monitormonitor

Cathode ray tubeCathode ray tube Vertical sectionVertical section Horizontal sectionHorizontal section High voltage sectionHigh voltage section Switch mode power supplySwitch mode power supply

Cathode ray tubeCathode ray tube

CRT is the main part of a monitorCRT is the main part of a monitor CRT converts electrical signals in to visual CRT converts electrical signals in to visual

informationinformation It consist of a vacuum tube enclosed in glassIt consist of a vacuum tube enclosed in glass One end of the tube contains an electron One end of the tube contains an electron

gungun The other end consist of screen with The other end consist of screen with

phosphor coatingphosphor coating The phosphor has a property called The phosphor has a property called

persistencepersistence

Diagram of monochrome Diagram of monochrome CRTCRT

HeaterHeaterIt is used to heat the cathodeIt is used to heat the cathode

CathodeCathodeEmits the electron beam towards the Emits the electron beam towards the

screen according to the video signal screen according to the video signal appliedapplied

Control gridControl gridIt determines the intensity of the It determines the intensity of the

electron beam there by the brightness of electron beam there by the brightness of the monitorthe monitor

Accelerating gridAccelerating gridThis grid increases the velocity of the This grid increases the velocity of the

electron beam so that the beam reaches electron beam so that the beam reaches screen in a very short periodscreen in a very short period

Focus gridFocus gridThis grid sharpens the electron beam This grid sharpens the electron beam

to hit the specific dot on the phosphorous to hit the specific dot on the phosphorous screenscreen

Final anodeFinal anodeFinal anode is connected to 12-17KV Final anode is connected to 12-17KV

to attract the electron beamto attract the electron beam

Deflection yokeDeflection yokeIt is mounted close to the neck It is mounted close to the neck

of the tube and they move the of the tube and they move the electron beam to any desired electron beam to any desired location on the screenlocation on the screen It It is composed of two types of is composed of two types of deflection coils,they are horizontal & deflection coils,they are horizontal & vertical deflection coilvertical deflection coil

Pixel(dot)Pixel(dot) Dot pitchDot pitch ScanningScanning Horizontal scanningHorizontal scanning Vertical scanningVertical scanning FrameFrame Frame rate/Refresh rateFrame rate/Refresh rate BandwidthBandwidth Interlaced scanningInterlaced scanning Non interlaced scanningNon interlaced scanning

Depending on the CRT Depending on the CRT usedused

Classify in toClassify in toMonochrome monitorMonochrome monitor

colour monitorcolour monitor

Monochrome monitorMonochrome monitor

Mono means one and Chrome Mono means one and Chrome means colourmeans colour

They shows their images in one They shows their images in one colourcolour

Monochrome displays generally Monochrome displays generally availableavailable TTL monochromeTTL monochrome

Composite Composite MonochromeMonochrome VGAVGA

Multi Multi scanning monochromescanning monochrome

Basic block diagram of Basic block diagram of monochromemonochrome

The video signal from the display The video signal from the display card is fed to the monitorcard is fed to the monitor’’s video s video amplifier circuit amplifier circuit

Video driver will drive the cathode Video driver will drive the cathode that means cathode will emit electrons that means cathode will emit electrons according to the driveraccording to the driver’’s output s output

The Vsync pulses are fed to the The Vsync pulses are fed to the vertical oscillator which generates the vertical oscillator which generates the required frequency for vertical required frequency for vertical scanning. scanning.

Hsync pulse is fed to the Horizontal Hsync pulse is fed to the Horizontal oscillator which generates the oscillator which generates the required frequency for horizontal required frequency for horizontal scanning scanning

The flyback transformer generates The flyback transformer generates the required high voltage the required high voltage

SMPS provides the different SMPS provides the different voltages for different circuits voltages for different circuits

Colour monitorColour monitor

The main difference between colour The main difference between colour and monochrome monitor is its CRTand monochrome monitor is its CRT

The colour CRT has 3 different The colour CRT has 3 different colour Phosphor dots on its CRT face colour Phosphor dots on its CRT face

The phosphor dots are arranged as The phosphor dots are arranged as a triangle (TRIADS )a triangle (TRIADS )

It has three electron gun for It has three electron gun for emitting three electron beamemitting three electron beam

shadow maskshadow mask Aperture Grille(slot mask) Aperture Grille(slot mask) ConvergenceConvergence Purity magnetsPurity magnets Aspect ratioAspect ratio Horizontal sectionHorizontal section Vertical sectionVertical section Video sectionVideo section ResolutionResolution

Types of colour monitorTypes of colour monitor

Depending on the input signalDepending on the input signal

CompositeComposite

TTLTTL

AnalogAnalog

Block diagram of colour Block diagram of colour monitormonitor

Disadvantages of CRTDisadvantages of CRT

CRT is big in sizeCRT is big in size It uses more amount of powerIt uses more amount of power Its weight is highIts weight is high

So that it is not suited for So that it is not suited for Laptop computers Laptop computers

LCDLCD

Liquid crystal display Liquid crystal display Invented in 1960 which led the innovation Invented in 1960 which led the innovation

of LCD technologyof LCD technology These are organic compounds that These are organic compounds that

exhibit characteristic of both solids and exhibit characteristic of both solids and liquidsliquids

Low power consumption,light weight,and Low power consumption,light weight,and ruggednessruggedness

Which glow on their own,emitting Which glow on their own,emitting photons of visible lightphotons of visible light

They have capability to align their They have capability to align their crystalline structure so they can crystalline structure so they can change the polarity of the light that change the polarity of the light that passes through them.passes through them.

If an electric field is applied to these If an electric field is applied to these crystals ,their alignment can be crystals ,their alignment can be changedchanged

To make patterns visibleTo make patterns visible

Block reflected light (Reflective Block reflected light (Reflective LCD)LCD)

Backlit LCD (The light Backlit LCD (The light generated by a secondary source generated by a secondary source either behind the LCD paneleither behind the LCD panel

Technologies used in Technologies used in LCD panelsLCD panels

Super twistSuper twist

Double super twistDouble super twist

Triple super twistTriple super twist The twist of the crystals controls The twist of the crystals controls

the contrast of the screenthe contrast of the screen

Types of LCDTypes of LCD

Based on how the current that Based on how the current that aligns the moleculesaligns the molecules

Passive matrixPassive matrix

Active matrix(TFT technology)Active matrix(TFT technology)

Response time: Charging and Response time: Charging and discharging individual pixels discharging individual pixels requires a finite time requires a finite time

Field emission displaysField emission displays

Fed panel is essentially a flattened Fed panel is essentially a flattened vacuum tube vacuum tube

It is used as a wall hung displaysIt is used as a wall hung displays It is used in 10 inch note book It is used in 10 inch note book

displaysdisplays It uses the basic illumination It uses the basic illumination

principleprinciple The operational voltage is lowThe operational voltage is low Its response time is lower than LCDIts response time is lower than LCD

They have several number of cone shaped They have several number of cone shaped cathode emitters for serving each image cathode emitters for serving each image pixelpixel

At the other side,each pixel has a At the other side,each pixel has a conventional trio of phosphor dotsconventional trio of phosphor dots

Each dot have a transparent anode that Each dot have a transparent anode that attracts the electron fluxattracts the electron flux

It offers wider viewing angle than LCD It offers wider viewing angle than LCD about 160 degreeabout 160 degree

GAS PLASMAGAS PLASMA

The newest entrant in the field of The newest entrant in the field of Flat panel display system Flat panel display system

It uses high power than LCDIt uses high power than LCD It uses a grid of X and Y elements It uses a grid of X and Y elements

that address individual picture that address individual picture elementselements

Each picture element is filled with a Each picture element is filled with a gas like XENON,NEON which kept gas like XENON,NEON which kept at lower pressureat lower pressure

They emits ultraviolet light when we They emits ultraviolet light when we apply high electric potentialapply high electric potential

Rays activate the Red,Green and Rays activate the Red,Green and Blue phosphor dotsBlue phosphor dots

The draw back is ,the time to switch The draw back is ,the time to switch onon

T overcome this a constant voltage is T overcome this a constant voltage is applied to these cells to keep activeapplied to these cells to keep active

This reduces the overall contrastThis reduces the overall contrast