Plotter applications
A plotter gives a solid line. An injet printer
makes lines out of dots. Plotters are somtimes used to make photomasks for pcb's where you need solid lines, small gaps between dots on a printed mask could make open circuit tracks.
Plotters were generally used for technical drawings such as building plans, mechanical drawings and circuit diagrams. Pen plotters were used twenty years ago when a typical printer was a dot matrix type with poor resoloution.
>why do we use plotter when we have cheaper printers?
These days people usually don't use plotters. High resolution inkjet printers are usually used instead of plotters.
I search briefly with google and could not find any new pen plotters for sale.
I bought a secondhand **broken link removed** for almost nothing years ago and used a pen filled with permanent marker ink to plot tracks directly onto copper-clad board to make prototype pcb's, mainly for the novelty. I still have it somewhere but the driver was for windows 3.1, a cheap inkjet is much better and much faster for diagrams and there are lots pcb manufacturers that make single pcb's very cheap.