Editing Stored energy printer

{{Short description|Type of computer printer}}
{{More citations needed|date=March 2025}}
A '''stored energy printer''' is a [[Printer (computing)|computer printer]] that uses the energy stored in a spring or [[magnetic field]] to push a hammer into a [[ink ribbon|ribbon]] to print a dot. It is a type of impact printer.<ref>{{cite journal |last1=Hendriks |first1=Ferdinand |title=Bounce and Chaotic Motion in Impact Print Hammers |journal=IBM Journal of Research and Development |date=May 1983 |volume=27 |issue=3 |pages=273–280 |doi=10.1147/rd.273.0273 |url=https://ieeexplore.ieee.org/document/5390421 |access-date=29 March 2025 |issn=0018-8646}}</ref> 

As compared to [[dot matrix printer]]s that print a single column of dots at a time, this printer generally creates an entire line of dots at a time. Therefore, it is also known as a [[line matrix printer]].{{Clarify|date=March 2025}}

An advantage of this technology is its low running costs: printer hammers have a lifespan of millions to billions of dots, and ink is transferred using conventional typewriter-style ribbons.

==Technology==
The most common printer to use this technology was the line-matrix printer made by [[Printronix]] and its licensees. In this type, the hammers are machined from an oval of magnetically permeable stainless steel, and the hammer-tips form vertical rows. The hammers are arranged as a "hammerbank"; a type of comb that oscillates horizontally to produce a line of dots. The original technology was patented by Printronix in 1974.<ref name="Romano">{{cite book |last1=Romano |first1=Frank |title=Color Desktop Printer Technology |date=22 February 2006 |publisher=CRC Press |isbn=978-0-8247-5364-1 |pages=85–107 |language=en |chapter=The Business and Market for Desktop Printers}}</ref>

The [[tungsten carbide]] hammer is [[Brazing|brazed]] to the center-top of a [[leaf spring]]. The top of this stiff spring is initially held back by a [[magnet]]ic pole-piece. To produce a dot, an [[electromagnetic coil]] wrapped around the pole-piece neutralizes the magnetic field, causing the spring to release the hammer and hit the ribbon and the paper behind it, leaving behind the printed dot.{{Citation needed|date=March 2025}}

Character matrix printers have also been produced.<ref name="Romano"/>

==Improvements==
Recent{{When|date=March 2025}} designs have performed complex optimizations in the magnetic circuit, and eliminated unwanted [[resonance]]s in the spring. The result was a near-doubling of speed. Other improvements include the use of [[electrical discharge machining]] to produce complex, three-dimensional hammers that trade-off the magnetic circuit, mechanical resonances, and printing speed.

Normal wear occurs on the pole piece when the spring rubs against it as it returns. This eventually requires the pole pieces to be reground and recertified. However, using [[Hexavalent chromium|hexavalent]] [[chrome plating]] on the pole-piece, combined with careful design,{{specify}} more than doubles speeds and improves life-span, allowing approximately a billion impressions per hammer.

==References==
{{reflist}}

[[Category:Computer peripherals]]
[[Category:Computer printers]]
[[Category:Impact printers]]
[[Category:Printing technology]]

{{computing-stub}}