Photocopiers work based on a technology called xerography, which involves using static electricity, light, and toner to produce copies of documents. Here’s a simplified explanation of how a photocopier works:
- Exposing the Document: When you place a document on the glass platen of a photocopier, the photocopier’s scanning system captures the image of the document using light. The light scans across the document’s surface, converting the content into a pattern of electrical charges.
- Charging the Photoreceptor Drum: Inside the photocopier, there’s a cylindrical drum called the photoreceptor drum. It’s initially given a uniform positive charge using a corona wire or another charging method.
- Exposing the Drum: As the light scans the original document, the areas that are white (blank) will reflect more light and those that are dark (printed) will reflect less light. This creates a pattern of charges on the photoreceptor drum that corresponds to the document’s content.
- Developing: A toner, which is a fine powder containing pigments, is given a negative charge. The toner is attracted to the areas on the photoreceptor drum that have a positive charge, sticking to these charged areas and forming an “invisible” copy of the document.
- Transferring: A piece of paper is given a positive charge. The toner on the photoreceptor drum is attracted to the paper, transferring the toner image onto the paper.
- Fusing: The paper with the toner image is passed through a fuser unit. The fuser unit applies heat and pressure to melt the toner particles and fuse them onto the paper permanently, creating the final copy.
- Cleaning and Erasing: After the toner is transferred, any remaining toner on the photoreceptor drum is cleaned off using a cleaning blade or roller. Any residual charge on the drum is neutralized by an eraser lamp or other methods, preparing it for the next copy.
