Output devices Objectives: To understand what output devices are. Identify their individual uses Be able to identify when it is best to use a specific output device.

Output Methods Before any output can be produced by a computer it must have an output device connected to it. The output devices that you are probably most used to will be: Screen. Monitor. Printer. Another sort of output that you will have experienced when using a computer is sound, which is output through a speaker.

Monitor A monitor or screen is an output device that can display graphics and text and video. The picture on a monitor is made up of thousands of tiny coloured dots called pixels. The quality of the output on a monitor depends on its resolution. The resolution of a monitor depends on the number of pixels that it can display.

Dot matrix printers A dot matrix printer forms characters and graphics on the paper by producing patterns of dots. If you look closely at a print-out from a dot matrix printer you will see the tiny dots which make up the printout. The part of the printer which forms the patterns of dots is called the print head. The print head is made up from pins which are pushed out in different arrangements to form the various patterns of dots needed.

Inkjet printers Inkjet printers work like dot matrix printers The printouts that they produce are made up of patterns of very small dots but the print head has a set of tiny holes rather than pins. As the print head moves across the paper ink is forced out through the holes to form the image. Inkjet printers are very quiet to operate and can produce good-quality printouts of both graphics and text. Relatively cheap colour graphics can be printed using a colour inkjet.

Laser printers Laser printers give very high-quality printed output of both text and graphics very quickly and quietly. They are generally more expensive to buy than inkjet printers. The toner cartridges are more expensive. They are ideal for large volume printouts because of their speed.

Plotters The main difference between a plotter and a printer is that a plotter uses a pen to draw the computer output onto the paper. Some plotters use a set of coloured pens to produce colour output. Plotters produce very accurate drawings and are often used in computer aided design or CAD.

Speakers Computers can output music, voices and many other complicated sounds using speakers. To be able to output sound a computer needs to have a special circuit board inside it called a sound card.

Some Questions??? A company wants to buy a printer for its office. What factors would be important when deciding what type of printer to buy?

Some Questions??? What type of output device would be most suitable for each of the following applications: Give at least one reason for each of your choices. (a)General printing on a home computer, including printing letters and other documents. (b)Printing in a busy office. (c)Printing customer receipts in a supermarket. The printer must produce a second copy for the supermarket to keep on self replicating paper (paper that copies through where pressure has been applied to the top copy).

Some Questions??? (d) Producing lists of theatre seats that are available when a customer telephones to book a ticket. (e) Producing high quality output for a design studio. (f) Producing architectural drawings. (g) Producing a warning that a library book that has just been returned is overdue and a fine should be paid.