INTRODUCTION TO COMPUTER CHAPTER N0 2 INPUT & INPUT & OUTPUT DEVICES OUTPUT DEVICES INSTRUCTOR: ADEEL ANJUM ADEEL ANJUM

OUTPUT DEVICES An output device is used by computer to communicate its results or message to the outer world. An output device is used by computer to communicate its results or message to the outer world. A device which transfers the data or program from computer memory to outer medium. For example the monitor or printer. A device which transfers the data or program from computer memory to outer medium. For example the monitor or printer. Almost every computer will include a device that outputs data in human readable form. Almost every computer will include a device that outputs data in human readable form. A small computer will only have cathode ray tube (monitor) on which the output appears temporarily. A small computer will only have cathode ray tube (monitor) on which the output appears temporarily. Example:monitor,printer,plotter,speakers,VCR, etc. Example:monitor,printer,plotter,speakers,VCR, etc.

What are two categories of output data? What are two categories of output data? Soft copy and hard copy are two categories of output data. Soft copy and hard copy are two categories of output data.  SOFT COPY it is data that is shown on display screen or is in audio or video form it exist only electronically. it cannot be touched. its like music.  HARD COPY it is printed output. for example print out.  MONITOR  There are two types of monitor CRT and FLAT PANEL.  CRT (cathode ray tube) The monitor is referred to as the CRT i.e. the cathode ray tube. It is very popular output device as far as the communication with the computer is concerned. The monitor is similar to a television screen and in fact for some computers the television screen can be used as the monitor. In 1897 German physicist invented CRT.  FLAT PANEL It is made up of two plates pf glass separated by a layer of a substance in which light is manipulated. It use liquid crystal display (LCD) technology. It is much thinner,weight less,portable,consume less power as compares to CRT.

 PRINTER Printer is output device used to prepare permanent document on a paper for human use. Printer is output device used to prepare permanent document on a paper for human use. A computer peripheral that puts text or a computer generated image on paper or on another medium. A computer peripheral that puts text or a computer generated image on paper or on another medium. Printer can be categorized in several ways the most common distinction Printer can be categorized in several ways the most common distinction IMPACT and NON-IMPACT. IMPACT and NON-IMPACT.

 IMPACT PRINTER Is the method used by the conventional typewriters? In some type of impact printing a metal "hammer" embossed with a character strikes a print ribbon, which presses the characters image into paper. In other types the hammer strikes the paper and presses it into the ribbon characters created through impact printing can be formed by either a solid font or dot matrix printing mechanism. TYPES OF IMPACT PRINTER.  LINE PRINTER  DOT MATRIX PRINTER  DAISY WHEEL PRINTER 5

 LINE PRINTERS Any printer that prints one line at one time, as opposed to one character at a time. Line printer typically produced the 11 by 17 inch "computer" printout. They are high-speed devices and are often used with mainframes, minicomputers, or networked machines rather than with single user system. Types of line printers include chain printers and band printer.  DOT MATRIX PRINTER Any printer that produces character made up of dots using a wire pin printed head. The quality of output from a dot matrix printer depends largely on the number of dots in the matrix, which might be low enough to show individual dots or might be high enough to approach the look of fully formed characters. The number of pins in the printer head typically, 9 or 24 often categorizes dot matrix printers.  DAISY WHEEL PRINTER Daisy wheel printer are some times called letter quality printer because they are often used to produce attractive correspondence. The D.W.P is a flat circular device made of metal with character embossed on it. As this wheel spins at a very high speed the hammer hits the specific character against the ribbon which presses against the paper. 6

 NON – IMPACT PRINTING Does not depend on the impact of metal on paper. In fact no physical contact at all occurs between the printing mechanism and the paper. TYPES OF NON IMPACT PRINTERS  LASER PRINTER  INK JET PRINTER  THERMAL PRINTER  PLOTTER 7

 LASER PRINTERS An electro photographic printer that is based on the technology used by photocopiers. A focused laser beam and a rotating mirror are used to draw an image of the desired page on a photosensitive drum. This image is converted on the drum into an electrostatic charge, which attracts and holds toner. A piece of electro-statically charged paper is rolled against the drum, which pulls the toner away from the drum and onto the paper. Heat is then applied to fuse the toner to the paper. Finally, the electrified charge is removed from the drum and the excess toner is collected. By omitting the final step and repeating only the toner application and paper handling steps, the printer can make multiple copies. Laser printer run with a software called page description language (PDL).It has its own CPU,ROM,RAM. An electro photographic printer that is based on the technology used by photocopiers. A focused laser beam and a rotating mirror are used to draw an image of the desired page on a photosensitive drum. This image is converted on the drum into an electrostatic charge, which attracts and holds toner. A piece of electro-statically charged paper is rolled against the drum, which pulls the toner away from the drum and onto the paper. Heat is then applied to fuse the toner to the paper. Finally, the electrified charge is removed from the drum and the excess toner is collected. By omitting the final step and repeating only the toner application and paper handling steps, the printer can make multiple copies. Laser printer run with a software called page description language (PDL).It has its own CPU,ROM,RAM.  THERMAL TRANSFER PRINTER It is a kind of non-impact printer. In electro-thermal printing, characters are burned on to a special paper by heated rods on a print heat. They transfer ink from a wax-based ribbon onto plain paper. These printers can support high quality graphic. It is a kind of non-impact printer. In electro-thermal printing, characters are burned on to a special paper by heated rods on a print heat. They transfer ink from a wax-based ribbon onto plain paper. These printers can support high quality graphic. 8

 INK – JET PRINTER It is a kind of non-impact spray small dots of electrically charged ink onto a paper to form images. Ink jet printers are flexible enough to be used as plotters. It is a kind of non-impact spray small dots of electrically charged ink onto a paper to form images. Ink jet printers are flexible enough to be used as plotters.  PLOTTER The plotter is an output device. It is an example of non impact printer. plotters are designed to produce large drawing or images such as construction plan for buildings. The plotter is an output device. It is an example of non impact printer. plotters are designed to produce large drawing or images such as construction plan for buildings. 9