How A Photocopier Works
Photocopiers function because of the principle of ‘opposite charges attract’. Below are the six main steps in the photocopying process:
Charging: The part of the photocopier called a drum is electrostatic-ally charged. The drum has a photo-conductive coating which becomes conductive upon exposure to light.
Exposing: A bright light passes over the document to be copied. The part of the document which is coloured white reflects the light on the photo-conductive drum and it becomes positively charged. Meanwhile, the parts which are dark or black remain negatively charged.
Developing: The positively charged toner is attracted by the negatively charged areas of the reflected image.
Transferring: The toner is then transferred from the drum onto a piece of paper. A stronger negative charge is applied to the paper to attract the toner.
Fusing: The paper then passes through heated rollers to melt the toner and bond it onto the paper. This is why papers coming out of the copy machine are warm.
Cleaning: To ensure that the residual toners are removed from the photo-conductive drum and prepare it for the next image, photocopiers have rotating brushes that cleans it after every photocopying process.
The process used by modern digital photocopiers is not different from the process mentioned above. However, there are some improvements in the methods such as the change from the exposing process into an image scanning process. This enables the photocopier to remember the image to be copied and to make copies faster.