Fotocopy machine technology

[Chamith119]

i want to know how to working fotocopy machin. toner machine . i searched the web . but i can,t found good web site or pdf.

thanx

[Neo]

Xerography (or electrophotography) is a dry photocopying technique invented by Chester Carlson in 1938, for which he was awarded U.S. Patent 2,297,691 on October 6, 1942. Carlson originally called his invention electrophotography. It was later renamed xerography—from the Greek roots ????? xeros "dry" and -?????? -graphia "writing"—to emphasize that, unlike reproduction techniques then in use such as cyanotype, this process used no liquid chemicals.

Although Georg Christoph Lichtenberg invented a dry electrostatic printing process in 1778, Carlson's innovation combined electrostatic printing with photography. Carlson's original process was cumbersome, requiring several manual processing steps with flat plates. It was almost 18 years before a fully automated process was developed, the key breakthrough being use of a cylindrical drum coated with selenium instead of a flat plate. This resulted in the first commercial automatic copier, the Xerox 914, being released by Haloid/Xerox in 1960. Xerography is used in most photocopying machines and in laser and LED printers.

Basic steps involved in Xerography

1. Charging: cylindrical drum is electrostatically charged by a high voltage wire called a corona wire or a charge roller. The drum has a coating of a photoconductive material. A photoconductor is a semiconductor that becomes conductive when exposed to light.
2. Exposure: A bright lamp illuminates the original document, and the white areas of the original document reflect the light onto the surface of the photoconductive drum. The areas of the drum that are exposed to light become conductive and therefore discharge to ground. The area of the drum not exposed to light (those areas that correspond to black portions of the original document) remain negatively charged. The result is a latent electrical image on the surface of the drum.
3. Developing: The toner is positively charged. When it is applied to the drum to develop the image, it is attracted and sticks to the areas that are negatively charged (black areas), just as paper sticks to a toy balloon with a static charge.
4. Transfer: The resulting toner image on the surface of the drum is transferred from the drum onto a piece of paper with a higher negative charge than the drum.
5. Fusing: The toner is melted and bonded to the paper by heat and pressure rollers.

Further reading:
Photocopier
Xerography
How Photocopiers Work
How Does a Photocopy Machine Work?
How Photocopiers Work – A Clear Picture

[Chamith119]

thanx you very very much bro

[SemiconductorCat]

thanks neo, I learn this now today.
I read your response , it's clear and concise.
+1 for that.