Cathode Ray Tube (CRT) VERTICAL ELECTRON PHOSPHOR DEFLECTION GUN COATED FOCUSING PLATES SCREEN BASE SYSTEM HORIZONTALCONNECTOR DEFLECTIONPINS ELECTRON PLATES BEAM
RESOLUTION• The maximum number of points that can be displayed without overlap on a CRT.• The number of points per centimeter that can be plotted horizontally and vertically.
PLASMA PANELS• Also called gas-discharge displays.• Constructed by filling the regions between two glass plates with a mixture of gases that usually includes neon.• Firing applied to a pair of horizontal and vertical conductors cause the gas at the intersection of the two conductors to break down into a glowing plasma of electrons and ions.
Light-Emitting Diode (LED)• A matrix of diodes is arranged to form the pixel positions in the display.
Liquid Crystal Display (LCD)• These produce picture by passing polarized light from the surroundings or from the internal light source through a liquid-crystal material that can be alligned to either transmit or block the light.• The main principle behind liquid crystal molecules is that when an electric current is applied to them, they tend to untwist. This causes a change in the light angle passing through them. This causes a change in the angle of the top polarizing filter with respect to it. So little light is allowed to pass through that particular area of LCD. Thus that area becomes darker comparing to others.
LASER PRINTER• It uses a very fine powder known as ‘Toner’.• The photoconducting drum which is the key component of the laser printer has a special coating which receives the positive and negative charge from a charging roller.• A rapidly switching laser beam scans the charged drum line by line. When the beam flashes on, it reverses the charge of tiny spots on the drum, respecting to the dots that are to be printed black.• As soon the laser scans a line, a stepper motor moves the drum in order to scan the next line by the laser.• A developer roller is coated with charged tonner particles. As the drum touches the developer roller, the charged tonner particles cling to the discharged areas of the drum, reproducing your images and text reversely.• As the paper passes through a charging wire it applies a charge on it opposite to the toner’s charge.• When the paper meets the drum, due to the opposite charge between the paper and toner particles, the toner particles are transferred to the paper.
INK-JET PRINTERS• At the heart of an ink jet printer are a large number of high-precision microscopic nozzles which eject ink onto the paper.• The ink jet nozzles are all mounted together on a moving carriage assembly that moves at high speed back and forth across the paper.• Ink drops are commonly printed at a resolution of 600 or 1200 dots per inch.• Optical encoders precisely control the location of the printed dots, both across and down the page.