Xerograafiat

Xerograafiat, also known as xerography, is a dry copying process that uses electrostatic charges to make copies of documents. The term "xerography" comes from the Greek words xeros (dry) and graphein (to write). This technology was invented by Chester Carlson in 1938 and was first commercially developed by the Haloid Company, which later became Xerox Corporation.

The xerographic process involves several key steps. First, a photoreceptor drum, typically coated with a photoconductive material like selenium, is electrostatically charged. Next, an image of the original document is projected onto the drum. In areas where light strikes the drum, the photoconductive material loses its charge. The charged areas remain, forming an electrostatic image. A powdered ink, called toner, is then applied to the drum. The toner particles are attracted to the charged areas, adhering to the electrostatic image.

After the toner has transferred to the drum, it is transferred to a sheet of paper. The paper is given an opposite electrostatic charge, causing the toner to be pulled from the drum onto the paper. Finally, the toner on the paper is fused into place using heat and pressure, creating a permanent copy. Xerography revolutionized document reproduction, making it faster and more accessible than previous methods. It forms the basis of modern photocopiers and laser printers.