Printer Copier Components
As the only significant difference between the printer function and the digital copier function is the network connection source of original image to print, the components are much the same, but highly dependent on whether the printer copier uses a laser printing or inkjet printing mechanism.
A light emitting laser gun is controlled by the printer electronics to fire light pulses towards mirrors, which reflect the light onto the photosensitive drum to form the image as static electricity. This is not a component that can be replaced by the consumer, but is fundamental to the laser printing process.
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 the 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 ribbon is a piece of material that carries wiring from the electronic circuitry to the printhead which houses the ink cartridges. The electronic circuit sends information through the ribbon to control the motion of the printhead across the paper according to the image formation of the document to print.
At the same time, heat is transferred through the ribbon to the print cartridges and is only applied when ink needs to be released.
The printhead is a casing that houses the ink cartridges, with specifically sized openings at the bottom to released the ink through, and has the ribbon attached to the back with a mechanism to transfer the signals from the control circuit which the ribbon is attached to on the other end.
The printhead sits on a horizontal pole which is placed at a particular distance above the passing paper; enough for the printhead to slide across the pole to specific positions according to where the image needs to be printed onto the paper.
Inkjet ink cartridges are tubes containing different dye inks, but has an electronic chip to collect heat energy, which then creates and air bubble in the tube, and displaces ink which is released at an opening which sits aligned with an opening on the printhead to release into onto the paper in a controlled flow.
For colour printers, there are typically 5 cartridges, where four are the colours, black, magenta, cyan and yellow. The fifth is usually a larger cartridge with black also, dedicated to black and white printing, as it is the most common colour and thus would cause disproportionate consumption of the black coloured cartridge.
CCD: 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 CCD is used for the copying process, to convert a scanned image into digital data.
Electronic Control Circuit: The purpose of the control circuit will vary depending on the machine functionality. Usually a switch connected to the user control panel will activate the specific function, whether to scan, copy or print.
For the copier function, the signal is passed from the CCD to a circuit board which will have an ‘Analogue to Digital Converter’. The output of the circuit passes the signal to the printing mechanism, whether laser or inkjet.
For the printer function, the document image is sent by a network connection from the computer and the circuitry accepts the data and passes the signal on to the printing mechanism.
In the laser printing mechanism, the information is sent through a light emitting laser gun to project the image as light again onto mirrors towards the photosensitive drum.
In the inkjet printing mechanism, the information causes electronic circuitry to control heat and movement through a ribbon attached to a printhead component.
Printer Output Attachment System: For mid to high volume printers, there are often physical attachment systems, such as for the output trays. This allows systems to be customized to business and printing volume needs, but generally the attachment systems are from the same manufacturer as the copier printer for output sections to fit together.
The attachments can have many or few paper trays for multiple, high volume printing, and can and automatic stapler as one of the output catch trays.
These variables of an attachment makes mid to higher volume printing more efficient, organised and time-effective.