PLASMA DISPLAY MONITOR

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• PLASMA DISPLAY MONITOR
• RASTOR VS RANDOM SCAN
• INTERLACING AND NON-INTERLACING

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PLASMA DISPLAY MONITOR
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WHAT IS PLASMA?

• Plasma is often called the "Fourth State of
  Matter", the other three being solid, liquid and
  gas. A plasma is a distinct state of matter
  containing a significant number of electrically
  charged particles, a number sufficient to affect
  its electrical properties and behavior.

Plasma is a substance similar to gas in which a
certain portion of the particles are ionized .
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INTRODUCTION

• A plasma display is the most advanced technology
  based display devices (as they are not at all
  bulky when compared to CRTs).
• Provide a very good quality of picture which is
  sharp from every angle.
• They have a slim profile can be wall mounted.
• They have got high refresh rates and a faster
  response time, contributing to superior
  performance.
• The weight of a plasma display monitor that is,
  on average about 40 to 50 of the weight of a
  CRT-based monitor of similar screen size.

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INSIDE THE DISPLAY

• A plasma display monitor is composed of a front
  plate with pairs of display electrodes and a rear
  plate which contains address electrodes.
• In the front plate the electrodes are covered
  with a glass layer called the Dielectric Layer. A
  magnesium oxide coating, called the Protective
  Layer, is applied to this glass layer.

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IMAGE FORMATION

• The display electrodes are arranged in horizontal
  rows along the screen and the address electrodes
  are arranged in vertical columns. The vertical
  and horizontal electrodes form a basic grid.
• Within each cell, there are actually three sub
  cells, one containing a red , another a blue ,
  and a green phosphor. To generate color shades,
  the perceived intensity of each RGB color must be
  controlled independently .
• To ionize the gas in a particular cell, the
  plasma display's computer charges the electrodes
  that intersect at that cell.

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• When the intersecting electrodes are charged, an
  electric current flows through the gas in the
  cell .
• The current creates a rapid flow of charged
  particles, which stimulates the gas atoms to
  release ultraviolet photons.
• The released ultraviolet photons interact with
  phosphor material coated on the inside wall of
  the cell.. When an ultraviolet photon hits a
  phosphor atom in the cell, one of the phosphor's
  electrons jumps to a higher energy level. When
  the electron falls back to its normal level, it
  releases energy in the form of a visible light .

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What actually happens inside the cell?
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RANDOM vs RASTER SCAN

• When operated as a random-scan display unit, a
  CRT directs the electron beam only to the parts
  of the screen where a picture is to be drawn.

• In raster scan, the beam sweeps horizontally
  left-to-right at a steady rate, then blanks and
  rapidly moves back to the left, where it turns
  back on and sweeps out the next line (flyback).

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• Random displays have high resolutions
• Smooth lines are produced as the electron beam
  directly follows the line path
• Random-scan system's are generally costlier
• Random scan systems are designed to draw all the
  component lines of a picture 30 to 60 times each
  second
• Picture definition is stored as a set of line
  drawing commands in an area of memory referred to
  as refresh display file.

• Raster displays have less resolution
• Lines produced are ziz-zag as the plotted values
  are discrete
• Decreasing memory costs have made raster systems
  popular.
• Refreshing on raster scan displays is carried out
  at the rate of 60 to 80 frames/second
• Picture definition is stored in a memory area
  called the refresh buffer/frame buffer.

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INTERLACING

• Interlaced scan refers to one of two common
  methods for "painting" a video image on an
  electronic display screen by scanning or
  displaying each line or row of pixels.
• This technique uses two fields to create a
  frame. One field contains all the odd lines in
  the image, the other contains all the even lines
  of the image .

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NON-INTERLACED DISPLAY

• It is the opposite phenomenon of
  Interlacing. In this all the lines of frame are
  scanned in one pass.
• For higher resolution the non-interlaced
  display creates a better image as compared to
  Interlaced display. The scanning is done line by
  line in continuous fashion in non-interlaced
  display.

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