There are many applications of electrostatics, but for the sake of this article, we will cover only two i.e. Xerography and Inkjet Printers.
Xerography (Photocopier)
The copying process is called xerography. It is a combination of the Greek word Xeros and Graphos which means dry writing.
Principle
It works on the electrostatic principle that opposite charges attract each other.
Construction
- Drum: The heart of the machine is an Aluminium drum. It is coated with a layer of Selenium. Selenium is a photoconductor that conducts when exposed to light and is an insulator in dark.
- Lamp and Lens: The camp and lens arrangement provides light and focuses the image on the drum.
- Toner: It is a dry black powder negatively charged.
- Rollers: Heated pressure rollers are used to melt the toner onto the paper.
Working
When the positive charge is spread over the selenium, It will remain there as long as it remains in dark.
When the drum is exposed to an image, the dark and bright areas of the image produce similar areas on the drum. The dark portions keep their positive charge, whilst the light areas conduct and lose their positive charge. They become neutral.
In this way, a positively charged image of the document remains on the selenium surface.
Now spread a negatively charged toner over the drum. It sticks to the positively charged areas. So the toner is transferred onto a sheet of paper. Heated rollers melt the toner onto the paper, to produce a permanent impression of documents.
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InkJet Printers
An inkjet [printer is a type of printer that uses electric charge in its operation.
Principle
A charged particle is deflected when passes through a uniform electric field between two oppositely charged parallel plates.
Construction
- Printer Head: It consists of a nozzle with an ink pump. It shuttles back and forth across the paper.
- Charging Electrodes: It charges the ink droplets.
- Deflection Plates: They divert charge droplets into the gutter.
- Gutter: It collects unused ink.
Working
An inkjet print head ejects a steady flow of ink droplets. The charging electrodes charge the droplets that are not needed on the paper. Charged droplets are deflected into a gutter by the deflection plates. The uncharged droplets fly off straight onto the paper to print documents.
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Conclusion
Applications of electrostatics have revolutionized the printing industry, enabling faster and more efficient printing technologies such as Xerography and InkJet printing. These technologies have become indispensable tools for modern-day businesses and individuals.
Hope you enjoyed reading about the fascinating role of electrostatics in Xerography and InkJet printing technologies!
