ICT- Output Devices

Visual Display Unit (VDU)

• displays information or output from the computer on the screen
• a pixel is the smallest area on the screen that can be edited. A picture is made up of a number of pixels
• screen resolution is a measure of the quality of the image on the screen. The more pixels, the higher the resolution
• the cost of the monitor increases as size and resolution get bigger
• an LDC screen is much lighter and smaller than a typical desktop cathode ray tube (CRT) screen
• LCD screens do not require as much power, making them more energy efficient
• some VDUs have inbuilt speakers and a microphone, making them suitable for multimedia users
• modern VDUs have an inbuilt filtering system to help reduce eyestrain

Impact Printer

• The print head is made up of a series of pins laid out in rows and columns (a matrix). The print head strikes an ink ribbon, leaving an impression on the page. Characters are formed as a series of dots when the tiny pins strike the ribbon. The more pins in the print head, the better the quality of the printer.
• An impact (dot-matrix) printer:
• is useful when organisations need to produce carbon copy printouts such as invoices or delivery notes
• prints only in one colour
• costs less to produce multiple copies of data (using the carbon copy method)
• produces low-quality print compared to a laser printer
• can be noisy in the workplace

Laser Printer

• A laser printer is a non-impact printer which uses a toner kit to produce printouts. Some laser printer are manufactured as three-in-one devices to include a scanner, a photocopier and/or fax capabilities.
• Laser printers usually have their own memory where pages are temporarily stored before printing
• A laser printer:
• can print in black and white or colour
• is suitable for high-volume printing
• produces excellent print quality
• works at greater speeds than other printers

Inkjet Printer

• Is a non-impact printer which uses black and coloured ink cartridges to produce printouts. The ink is heated and then sprayed through the many nozzles or jets in the print head to form characters or images. An inkjet printer:
• can print in black and white or colour
• is suitable for home use to print photographs and small volumes of documents
• has high-quality print which slows down the speed of output
• is slow at producing output compared to a laser printer

Plotter

• Some plotters use electronically controlled pens while other are 'penless' plotter (raster plotters).
• A plotter:
• produces high-quality accurate and detailed diagrams
• is used be architects, surveyors, pattern makers and engineers
• can use a variety of paper sizes
• can draw characters of different sizes and different fonts to be added to the drawing

Speaker

• small internal speakers are standard in computers
• provides sound output through the sound card from a computer
• can output music as well as the spoken word
• is useful for visually impaired users
• can draw attention to an input error (e.g. a 'beep' is output when a barcode is incorrectly scanned)