Output device

Output device

1. Dot Matrix Printers

   • How? The print head contains a grid of pins and different combinations of pins are pushed out to form different characters. The print head then hits a carbon ribbon leaving an impact on the paper
   • Strengths: cheap and reliable/ Limitations: poor quality, slow and noisy

2. Ink-jet Printers

   • How? Operate by heating the ink as it flows through a set of tiny nozzles. The hearting process causes a small droplet of ink to form. This is then released as a single dot which forms part of a letter or image
   • Strengths: Cheap, reliable and good quality print outs Limitations: Slower than Laser, cant do bulk printing but good for home and small office use

3. Laser Printers

   • How? The print head contains a laser which emits a beam of light. A spinning multi-faced mirror directs the beams in a horizontal line across a rotating drum. On rotation the Drum picks up powdered ink ‘Toner’ which is then fused onto paper by heat and pressure.
   • Strengths: Fast, reliable and high quality print outs,relatively cheap, quiet and handle bulk printing/ Limitations: more expensive than ink-jets, toner cartridges are expensive

4. Plotters

   • How? Plotters are a specialist type of printer which is able to draw high quality images on very large pieces of paper. They are used by engineers, architects and map-makers to draw plans of buildings, diagrams of machines or large scale maps. A plotter uses a pen, ink-jet or a chemical/ electrostatic charge.
   • Pen: Strengths: least expensive/ Limitations: slow and some functions don't work
   • Ink-jet: Strengths:quiet and produce more details output than pen
   • Electrostatic: Strengths: Very high resolution outputs and fastest of the three/ Limitations: use very expensive chemicals

5. CRT VDU- Cathode Ray Tube Visual Display Unit

   • How? DCA convertor used it recieves information in the form of different voltage levels for each of the primary colours then this determines the colour of each pixel.
   • Strengths: Cheaper than LCD, high resolution and colour / Limitations: Large, not portable

6. LCD Monitors (Liquid Crystal Display)

   • How? Made up of multiple layers each performing an important function. Light is passed though a polarised filter that only allows through light waves that are vibrating horizontally. They then pass through a layer of liquid crystal cells They are arranged in a matrix and shown on screen. The light passes through the 2 primary colours then through another polarised filter allowing light waves vibrating vertically.
   • Strengths: Light, adaptable, small space, can be used for portable devices, can run on battery/ Limitations: Image quality can be poor, quite expensive