Output Devices

Output Devices

1. Plotters

   • Plotters operate by use of a pen, ink jet or an chemical/electrostatic charge
   • Used when precise, high-definition and large copies are needed.
   • 2 types of plotters; Drum Plotter and Flatbed Plotter
   • Pen: Least expensive plotter device but slow and some functions can't be performed.
   • Ink-jet: Quiet and can produce more detailed output than pen plotters
   • Electrostatic: Very high resolution and fast but use expensive chemicals

2. CRT VDU

   • A special adaptor coverts the computer's digital signal to an analogue signal (DAC). The adaptor receives information in the form of different voltage levels for the 3 primary colours which determines the colour of each pixel. Adaptors have different memory capacity which determines how much information can be used to define the pixel's colour. The combination of different intensities of the 3 primary colours will produce a full range of colours.
   • Size- take up a lot of room. Cannot be easily be used for smaller, portable devices. Requite more power to run and there can be problems regarding heat generation.
   • Reasonable price. Good quality of resolution and colour.

3. LCD Monitors

   • Made up of multiple layers, each performing an important function. Light emitted from a constant light source are polarised allowing horizontal waves through which then pass through a layer of liquid crystal cells.These cells are arranged in a matrix which relates to the pattern of pixels on the screen. The light passes through one of three filters, one for each primary colour. The light is polarised allowing vertical waves through, depending on this will differ the intensitys of red/green/blue, combined will create a pixel of a certain colour.
   • Light, adaptable, take up less space and can be used for small portable devices. Don't require as much energy as CRT monitors and can be battery ran
   • The screen has to be viewed face on. The 'refresh' time is slower than CRI's. Current problems maintaining image quality at a competitive price for larger screens.