The paper cassette, often also called the paper tray, is the container to hold the stack of paper sheets to print on.
The paper feed is a rubber piece that takes a sheet of paper from the paper cassette and sends it into the printer system, beginning with the registration rollers.
A soft rubber roller that collects the paper and passes it towards the drum.
The exposure lamp exists in most old and new systems that copy an original document, and its purpose is to supply light to the image of the original so the light reflects off a series of lenses and optical mirrors and projects the image onto the Drum.
The drum is an aluminum cylinder coated with a photoconductive (light sensitive) film. The photoconductive material reacts to the light and so the image is formed on the drum as a series of active and inactive areas of static electricity on the photoconductive material. The intensity of light – perhaps by reflecting the amount of colour or grey, black or white – from the original document provides an intensity of electrical charge on the photoconductive material, which is created by the charge corona.
The first of the two Corona components is the Charge Corona, which is a thin wire in a metal slide, usually part of the drum unit, with the purpose of producing an electrical charge on the Drum where the light reacts with the photoconductive film. This charge is to attract the toner to the drum, as the toner unit consists of a positively charged chemical.
Toner is a powder which contains finely grounded dye coloured plastic, and this will become ink when heated. The unit also consists of something called ‘Developer’ which is a finely grounded metallic chemical with that can be electrically charged. When the electrically charged Drum rolls passed the toner unit, the developer is attracted to the drum, and carries the toner along with it onto the drum. Where there are colour toners, the collection of toner units with different colour dyes sit in parallel within proximity of the drum.
Much like the Charge Corona, the Transfer Corona is a thin wire housed in a metal slide that electrically attracts the toner from the drum onto the copy paper. At the same time this component separates the electrically charged paper away from the drum so the paper can continue to the next stage of the process.
The Fuser Unit binds the toner to the paper, consisting of two rollers, of which the upper one is heated to melt the toner plastic and releasing the ink onto the paper as the paper passes through the rollers. The upper fuser roller is heated by a temperature-controlled lamp, and is coated with a non-stick (and therefore easily cleanable) silicon coating. The lower fuser roller is not heated, and is generally just a soft silicon rubber.
As the drum is not only charged but attracts the toner with developer material to form the copy image on the drum, the cleaning unit is designed to remove any residue of the substances that form on the drum after the Transfer Corona has transferred the necessary toner representing the image onto th paper. The cleaning unit consists of a magnetic roller and a cleaning blade. The cleaning blade is simply a silicone rubber strip attached to a metal bracket, and makes physical contact with the Drum to remove the residue.
The Paper Transport is a carriage system that holds together the process of copying by consisting of a series of rubber rollers and planes to facilitate the copy paper’s passage along the process.
The Paper Tray – also known as the ‘catch tray’ – is often an optional extension to the exit location for the copy paper, allowing the paper to stack more efficiently with less risk of paper falling off the printer exit shelf.
CCD and other Electronics
In digital copiers, there are additional components to digitise the copied image before it is transported to the physical copying process. These components include a CCD (Charge Couple Device) which acts as a sensor to the image light from the lamp/mirror, and converts it into a series of charges that represents the formation of the image from the light.
The signal is then passed on to other electronics on a circuit board within the copier, such as an ‘Analogue to Digital Converter’. On the output of the circuit, the signal is passed to a laser gun which forms the image as light again onto mirrors towards the photosensitive drum. The purpose of the electronics is to add a stage of refinement and flexibility to the copy.
Source : http://www.photocopier.org.uk/copier-components