Showing posts with label MONITORS. Show all posts
Showing posts with label MONITORS. Show all posts

Saturday, March 6, 2021

MONITORS IN SUMMARY

 

MONITORS

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 TP15 PIN VGA CONNECTOR TO THE MOTHERBOARD.

 

 THERE ARE TWO TYPES OF MONITOR TECHNOLOGY AVAILABLE TO THE MARKET.

HERE ARE THOSE

 

CATHODE RAY TUBE (CRT)

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 PICTURE TUBE CONTAINS AN ELECTRON GUN.  IT EMITS 3 ELECTRON BEAMS.  ONE EACH FOR RED, GREEEN, BLUE LIGHT.  THE FRONT END OF THE PICTURE TUBE IS COATED WITH PHOSPHOROUS. 

 

WHEN THE ELECTRON HITS PHOSPHOROUS COATING IT STARTS TO GLOW.  JUST BEFORE THE PHOSPHOROUS COATING A METAL PLATE CALLED SHADOW MASK IS USED TO DIVIDE THE IMAGE CREATED BY THE ELECTRON GUN INTO RED, GREEN AND BLUE PIXELS ON STRIPS THAT FORM THE IMAGE. 

 

SHADOW MASK USES ON OF THREE TECHNOLOGIES.  A PHOSPHOUR TRIAD, AN APERTURE GRILL, A SLOTTED MASK.  CRT MONITORS ARE BULKY TAKES MORE DISK SPACE,   CONSUMES MORE POWER AND EMITS MORE HEAT.  CRT MONITOR WAS 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 TODAY MARKET IS LED MONITOR SUPPRESED LCD MONITORS.  BECAUSE IT GIVES BETTER COLOUIR QUALITY, WIDE VIEWING ANGLE AND CONSUMES LESS POWER.  


 

IT USES LIQUID CRYSTAL CELLS TO POLARIZE THE LIGHT.   LCD MONITORS USES FLUOROSCENT LAMP AND LED MONITORS USES LED LAMPS FOR BAKCLIGHTING .  THIS DISPLAY USES AN ARRAY OF TRANSISTORS TO CONTROL EACH CELL.

 

VARIATION ARE THE COLOUR BIT, RESPONSE TIME  AND THE REFRESH RATE.   THIS MONITORS COMES WITH TWO TYPES OF TRANSISTOR TECHNOLOGY 1) PASSIVE MATRIX 2) ACTIVE MATRIX

 

PASSIVE MATRIX

 


A PASSIVE MATRIX DISPLAY DOESNOT HAVE A DEDICATED TRANSISTOR FOR EACH PIXEL OR SUB PIXEL,  BUT INSTEAD 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.

 

IT SENDS A SIGNAL ACROSS THE X AND Y COORDINATE TRACES THAT INTERSECT AT THAT PIXEL, THUS TURNING IT ON.  A 1366 X 768 RESOLUTION MONITOR CONTAINS 1366  TRANSISTOR AT THAT HORIZONTAL EDGE AND 768 TRANSISTORS AT THE VERTICAL EDGE.

 

THE VIEWING ANGLE IS A MOST UNCONSIDERABLE ISSUE OF A PASSIVE MATRIX DISPLAY.  THE PICTURE QUALITY IS MUDDY BECAUSE THE CONDUCTIVE TRACES SOMETIMES EFFECTS THE NEIGHBOURING IXELS OF A TARGET PIXEL

 

THE ONE ADVANTAGE OF PASSIVE MATRIX IS IT ONSUMES 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 SEPERATELY LEADING TO INCREASED QUALITY.

 

ALTHOUGH DUAL SCAN IMPROVES THE QUALTY 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 ALIGH 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 FROM ANY ANGLE.

 

IT DOESN’T REQUIRE AN SCAN REFRESHING TO MAINTAIN AN IMAGE, BECAUSE REANSISTORS CONDUCT CURRENT ONLY IN ONE DIRECTION AND THE PIXELS ACT LIKE A CAPACITOR BY HOLDING ITS CHARGE UNTIL IT IS REFRESHED

 

HIGHER REFRESH RATES ESULTS IN BETTER VIDEO OR GAING PERFORMANCE NOT FOR STILL IMAGE.   THE MAJOR DISADVANTAGE OF ACTIVE MATRIX SCREEN THAT IT REQUIRES MORE POWER TO OPERATE ALL TRANSISTOR.   EVEN IF THE BACKLIGHT IS TURNED OF THE SCREEN CAN STLL CONSUME POWER AT AN ALARMING RATE. 

 

ANOTHER PROBLEM WITH ACTIVE MATRIX IS LIGHT BLEED.

 

THANKS FOR READING.  I HOPE YOU LIKED IT.

Sunday, June 14, 2020

MONITORS: A COMPUTER PART


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 picture quality is muddy because the conductive traces sometimes affects the neighbouring pixels of a target pixel. The one advantage 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 separably 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 screen but it requires 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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