Plotters

A plotter is an output device used to produce hardcopy.

Plotters are used for a variety of applications, which include drawing graphs, making maps, plotting civil engineering drawings and machine components.

Plotters work on the principle of a human hand holding a pen and moving it on paper.

Plotters are normally very slow output devices because of excessive mechanical movement required during plotting but still plot much faster than a draughtsman and the output is of better quality.

Instead of the print cartridge found in a printer, a plotter commonly uses a pen.

With a plotter, a similar method of moving the paper and pen holder are used to allow the pen to be in precisely the right point at the right time.

However the order of print is different from a printer.

The pen does not start at the top right moving to the left and then down a line.

The plotter takes the whole image data, then calculates a path for the pen.

While the path for the pen may look complicated while the pen is in motion, In fact the plotter has calculated the shortest route for the pen, that involves the least amount of crossed lines as possible.

This not only makes the path more efficient, but also ensures there is the least possible chance of the final drawing getting smudged.

The pen plotters use one or multiple pens to plot the image on the paper.

Their speed varies between 15 to 30 inches per second of pen lines. The whole image to be plotted is controlled by various instructions used by the

computer as a series in one of the plotter control language.

Plotter move pen or pencil according to the instruction received from the computer in plotter control language. The most common plotter control language is HPGL i.e. Hewlett Packard Graphic Language. Other languages are DMPL ( Digital Microprocessor Plotter Language ) , HIPLOT ( Houseton Instruments Plotter Language ) etc.

It is a single pen plotter and drawing contains only one color then the plotting is

fastest.

The pen draws the image according to the instructions received from the computer.

But if it is a multicolor drawing then one needs to sit there and change the pens as and when required or prompted.

This decreases the speed of plotting and also one has to sit there and watch the job continuously.

On the other hand in case of a multipen plotter the pens are changed automatically by the main pen holder from the pen assembly.

The main pen holder collects the pens from assembly as and when required and it acts on the instructions supplied by the computer.

In most of the cases the plotter starts with one pen and draws all portions of drawing of that color then changes the second pen completes the portion of that color.

The process continues till all parts with all color of drawing is completed.

Because the pen is changed automatically so it is faster than single pen plotter in case of multicolor drawing but it needs an ink that must dry quickly enough so that lines are not subsequently smeared by the pen tip and also ink should not dry on the pen tip.

Also all the pens filled with inks must be ready to start the plotting.

Some electrostatic plotters are also available which are more faster than these plotters but they are very costly.

Their working principle is similar to that of laser printer. They create the whole image to be plotted in their memory first and it is

plotted as a series of dots. They are used for continuous outputs and a paper roll is used form then. How ever you can use cut sheets papers too, some other types of plotters

are thermal plotter , laser plotter and Pencil plotter.

The plotter are serial devices so they need serial ports for interfacing. Almost all plotters use the 25 pin D shell connectors for their interfacing. The 25 wired cable uses one 25 DM and one 25 DF connector at its ends. The female connector is attached to the computer and the male

connector is attached to the plotter.

ADDITIONAL READING IS STRONGLY RECOMMENDED