Output Devices

• Output devices take data produced by a computer and turn it into a human-readable form.

  Most common output devices are:

  • printers
  • screens
  • loudspeakers
  • multimedia projectors
• Inkjet printers are the most common form of printer. They range from small and inexpensive models to those that are used for professional photo printing.
• Inkjet printers often are sold at or below production cost, while the price of ink cartridges are dramatically marked up. Many inkjet printers will not print in black and white if a colour cartridge runs out. The cheaper water soluble ink tends to smear or blur with the smallest drop of moisture.
• Laser printers use toner powder instead of liquid ink. Toner is made of tiny plastic particles coated with carbon. Laser printers can produce high quality prints quickly but they tend to be more expensive than inkjets.
• Dot Matrix printers are also known as impact printers. They are similar to a typewriter as they strike an inked ribbon which imprints dots to form letters on the page. They can work effectively in damp atmospheres and are useful where multi-part stationary is required. However, they can be noisy, have a poor print quality and be expensive.
• 3D printers print using plastic filament, powdered resin, ceramic or metal powder. They can print intricate objects, including hollow areas.
• 3D printing can be applied in medicine through the use of printing prosthetic limbs.

  • huge reduction in cost and greater accuracy is matching limb to individual patient

  They can also be used for reconstructive surgery or general surgery

  • Can produce very accurate parts for a surgical procedure
• 3D printing can be applied in art and manufacturing for example manufacturing parts for cars. By using an existing part as a blueprint it is possible to print new components at a fraction of the cost. It will also be possible to print parts that are no longer available/being manufactured. You can also use 3D printing for prototyping designs in fashion and art which can save huge costs.
• Radio Frequency IF (RFID)


  RFID systems are Input/Output devices. They use a transponder and a receiver. The powered receiver emits radio frequency energy. The transponder antenna in the bank card, mobile phone or tag becomes energised by radio waves. The transponder can then send data to the receiver.
• RFID tag uses:

  • security control points or identification of people
  • shipping and supply chain tracking for goods
  • banking and fast-payment systems
  • as a potential replacement for barcode systems
• Passive Tags


  Passive transponders, used in bank cards for example, have no power source themselves and rely on the radio waves from the receiver for their energy.
• Active Tags

  Active tags use a larger, battery powered beacon which can broadcast its own signal to receivers up to 300m away. These are useful for larger items that are not placed on a receiver by hand. For example, in shipping, toll stations, warehousing and control points.
• Actuators

  Motors that are commonly used in conjunction with sensors to control a mechanism. For example, opening a valve or door, starting a pump.
• Loudspeakers and Headphones


  Digital data is sent from the computer to a digital to analogue converter (DAC) where it is converted into an analogue signal. The signal is then boosted using an amplifier and finally sent to a speaker.
• Liquid Crystal Display (LCD) Monitors

  The screen of an LCD contain groups of red, green and blue diodes to form each pixel. The monitor screen require backlighting using cold cathode fluorescent lamps (CCFL) or LEDs since the crystals act as a light valve and do not emit light themselves.
• LEDs vs CCFLs

  LEDs have many advantages over CCFLs:

  • They reach their maximum brightness almost immediately
  • The image is sharper with more realistic and vivid colours
  • They produce a brighter light which leads to better picture definition
  • LEDs are very small which allows the screens to be much thinner in construction
  • They last almost indefinitely which makes the screens much more reliable
  • They consume very little power and produce very little heat as well as reduce running costs
• Organic LED Screens

  They are much thinner and lighter than traditional LCD or LED screens

  • They are plastic rather than glass which makes them flexible
  • The light emitted from an OLED system is much brighter than the LCD or LED screens
• Benefits of OLEDs:

  • generate their own light so there is no need for the complexity of back lighting
  • less power is consumed; good for battery operated devices
  • little heat is produced
  • have a larger field of view than LCD screens - this can be further enhanced when the screen is curved
• Multimedia Light Projectors

  These are compact high resolution full-colour projectors. The can project text, images, video and audio content. Typically, the projector will input data from a computer, DVD/CD player or storage device.
• Multimedia Projector

  The projector takes a video signal, converts it into a viewable image and projects it on a screen. It can be used to present PowerPoint slide shows, TV, DVDs, video games and more.