A plotter is computer printing device to print vector graphics. Earlier plotters were used in CAD (Computer Aided Design) applications like construction maps or engineering drawing where precision is required. Nowadays old type plotters are being replaced with wide format printers.
Plotters draw images by moving a pen or similar type of instruments across the surface of a paper. This feature restricts plotters to line art. Pen plotters can draw continuous line while printers can simulate lines printing closely placed series of dots. But pen plotters are slower than printers because of the mechanical movements of the pen. Plotters could be of two types- black and white and colored. Different colored pens are used by multicolored plotters to draw in different colors. Generally printers are more economical that plotters.
Plotters are classified into two types- Drum plotter and Flatbed plotter.
Drum plotter:
Also known as roller plotter, this device comprises a drum or roller on which a paper is placed. The drum or roller rotates back and forth to sketch images on the paper. It also comprises a mechanical device called robotic arm that holds a set of colored pen or pencils. The robotic drawing arm makes sidewise movements while the paper is rolled back and forth by the drum or roller. Thus a graph or map is sketched on the paper. The plotter is controlled by a PC.
Flatbed plotter:
Also called table plotter, this device consists of flat bed or table, robotic pen arm or moving arm, primary pen, spare pen and pen cartridge. The drawing arms navigate over the stationary paper and sketch the map or graph on the paper. The average plot size is 20ft*50ft. it is widely used in the design of aircrafts, cars, ships, highways etc. The main drawback of this device is its speed. It is very slow in printing due to mechanical movements of the drawing arms.
Nowadays thermal ink jet and electrostatic plotters are preferred, compared to mechanical plotters.
