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.
