Dot Matrix

Stored Energy Printers

This type of dot matrix printer used the energy stored in a spring or magnetic field to make an impression on the ribbon thorough a hammer. The original technology was patented by Printronix in 1974. It consisted of tungsten-carbide hammers connected through a leaf-spring to a magnetic pole piece. A coil of wire wrapped around the pole piece would when needed neutralize the magnetic field causing the spring to snap the hammer away from the pole piece into a ribbon and then back.

The main advantage of stored energy printers was that they were very durable. The only wear and tear was that the spring would rub against the pole piece when it returned. Even so, the lifespan of each hammer would be around one billion impressions. Recent advances have allowed optimizations of the magnetic field and hammer shape leading to increases in lifespan by ten times and speed by two times. This type of printer has the lowest cost of printing per page since the only thing that is replaced regularly is the printing ribbon which is very inexpensive.

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