Display screens are of two types i.e. Cathode Ray Tubes and Flat Panel Displays CRT ( Cathode Ray Tubes ) : Types of Screen The most common form of display screen is the CRT . A Cathode Ray tube is a vacuum tube used as a display screen in a computer or video display terminal .
This same kind of technology is found not only in the screens of desktop computers but also in television set and in fight information monitors in airport is the types of Screen . A stream of bits defining the image is sent from the computer ( from the CPU ) to the CRT’s electron gun , where the bits are converted to electrons . The inside of the front of the CRT screen is coated with phosphor When a beam of electrons from the electron gun ( deflected through a yoke ) hits the phosphor , it lights up selected pixels to generate an image on the screen Deflection System Cathode Accelerating System Control Grid Focussing System Phosphor on inner surface and the types of Screen.
Types of Screen:
Flat – Panel Displays :
The flat – panel displays are much thinner , weightless , and consume less power to CRT Thus , they are better for portable computers Flat – panel displays are made up of two plates of glass with a substance in between them , which is activated in different ways . There are three types of technology used in flat – panel display screens LCD ( Liquid – Crystal Display ) consists of a substance called liquid crystal , the molecules of which line up im a way that lighting behind the screen is blocked or allowed through to create an image . EL ( Electro – Luminescent Display ) contain a substance that glow when it is charged by an electric current Gas – plasma display is like a neon bulb , in which the display uses a gas that emits light in the presence of a electric current Al present and the Types of Screen . EL and gas – plasma technology are more expensive thus are ne used as often as LCD technology.
Printers Printers are price pre They are divided into one Non – impact putem Impact Printers An imprinter la oharry mechanism such a primer winkel . an inwge on the paper Following are a few types of impact printers Det Matrix printerill contains a prethod of small pin wahre inked wibbon against paper for character wegen Primi trada availuhle with 0.18 or 24 pows , with the 24 – pin bond offer the best quale print Daisy – Wheel printer This printer uses a mechanism in the shape of series of petals arranged on a petal wheel having a character at the me onch petal is the types of Screen . A character comes into a print position by wheel rotation an image is formed by the hammer strike on the desired character i slower than dot – matrix printer but better in quality Line printer : This type of printer is normally used by mainframe minicomputers . It prints a whole line of characters at once rather tha single character at a time . Some of these can print up to 3000 lmes minute . It is of two types : chain printer and band printer Non – Impact Printers : Non – impact printer forms characters or impre without making direct physical contact between printing mechanism paper . There are three types in this category Laser Printer : It is similar to a photocopying machine and it use the principle of dot – matrix printers of creating images with dots . These image are created on a drum , treated with a magnetically charged ink – like tones these are the types of Screen .
Photoreceptor Drum Toner Coated Roller Charging Electrode ( Corona Wire ) Laser Scanning Unit Mirror.
( powder ) , and then transferred from drum to paper . The laser printer can produce high quality images of both text and graphics ( ranging from 300 dpi to 1200 dpi ) . Its speed varies from 4-32 text – only pages per minute for microcomputers and up to 200 pages per minute for mainframes . Ink – jet Printer : Ink – jet printer sprays small , electrically charged droplets of ink from four nozzles through holes in a matrix at high speed on to paper . It is cheaper compared to laser printer but lower in resolution ( 300 720 dpi ) and is slower also ( 1-6 ) text – only pages per minute . It has another type of printer i.e. bubble – jet printer , which uses miniature heating elements to force specially formulated inks through print heads with 128 tiny nozzles . Thermal Printer : Thermal printer uses colored waxes and heat to produce images by burning dots on to special paper . The colored wax sheets are not required for black – and – white output . It produces a high quality printout but is quite expensive compared to other non – impact printers . Plotters : A plotter is used to produce high – quality graphics in many colors and used for specialized applications i.e. architectural drawings , maps , graphs , and charts . Plotters are of two basic kinds : Flatbed plotter Drum plotter Flatbed Plotter : A flatbed plotter is the one , which has a paper lying flat on a table – like surface . The bed – size varies according to the need . One to four color pens move across the paper and the images are printed by the computer accordingly . Drum Plotter : It works like a flatbed plotter with a difference that the paper is mounted over a drum , enabling a continuous output . A typical usage is to track an earthquake readings . Sound Output : Speakers are most commonly used to have this type of output . Speaker : As we use microphone to input audio data to the computer , conversely we use speaker to get audio output from the computer . It works on the same principles to convert sound data into machine usable form . A variety of speakers are available in the market to satisfy the requirements of the users .