Selection and use of output methods, media, and devices: Printers AS Level ICT Selection and use of output methods, media, and devices: Printers Unit 1 Topic 6 - 06a - Output devices - Printers

Output methods Outputs come in a variety of different formats including: Hard copy (e.g. paper printouts) On-screen display (e.g. webpage) Digital outputs as inputs (e.g. a weather station’s output is sent in digital form to the National Weather Centre’s computer, where it becomes part of the inputs the computer needs to track and predict the national weather picture) Unit 1 Topic 6 - 06a - Output devices - Printers

Output methods Digital outputs to portable devices (e.g. files saved from a computer onto an IPod or MP3 player) Digital outputs as control signals (e.g. computer aided manufacture) Unit 1 Topic 6 - 06a - Output devices - Printers

Output devices Outputs devices include: Printers Screens (also called Visual Display Units) Plotters Speakers and headphones Any device that produces output media (e.g. Flash drives, removable hard drives, CD-ROMs, CD-RW, DVDs) Unit 1 Topic 6 - 06a - Output devices - Printers

Printers The main types of printers are: Ink-jet printers Laser printers Dot matrix printers Thermal printers Multifunctional printer Unit 1 Topic 6 - 06a - Output devices - Printers

Ink-jet printers Ink-jet printers are popular with home and small office users They work by spraying dots of fast-drying ink onto paper, and can produce both colour and black and white printouts

Ink-jet printers The dots are extremely small (usually between 50 and 60 microns in diameter, which is smaller than the diameter of a human hair [70 microns]) The dots are positioned very precisely, with resolutions of up to 1440 x 720 dots per inch (dpi) The dots can combine different colours together to create photo-quality images

Ink-jet printers The main components of an ink-jet printer are: The print head assembly Print head – contains a series of nozzles that are used to spray drops of ink Ink cartridge – this contains the ink that is sprayed through the print head Print head stepper motor – moves the print head assembly (print head and ink cartridges) back and forth across the paper

Ink-jet printers Print head Stepper motor

Ink-jet printers Belt – is used to attach the print head assembly to the stepper motor Stabiliser bar – is used to ensure that movement is precise and controlled

Stabiliser bar and belt Ink-jet printers Stabiliser bar and belt

Ink-jet printers The paper feed assembly Paper tray feeder Rollers – pulls the paper from the paper tray feeder and advances it when the print head assembly is ready for another pass Paper feed stepper motor - powers the rollers to move the paper in the exact amount needed to produce a continuous image Power supply Control circuitry Interface ports

Ink-jet printers Rollers

Ink-jet printers - Advantages Can produce high quality printouts (including photographs) Are quiet when operating Are cheap to buy

Ink-jet printers - Disadvantages Are costly to run (ink cartridges are expensive and the cost per page is higher than a laser printer) Can produce smudged images (the ink used will smudge if the printout is not handled properly, especially just after printing) Need special paper when producing photographic images

Laser printers Laser printers are popular with business users They work by using photocopier technology and toner to produce printed outputs

Laser printers

Laser printers Static electricity is what makes a laser printer work Static electricity is an electrical charge that builds up on an insulated object Because oppositely charged atoms are attracted to each other, objects with opposite static electricity fields cling together

Laser printers A laser printer uses this phenomenon as a sort of "temporary glue" The core component of this system is the photoreceptor, which is usually a revolving drum or cylinder This drum assembly is made out of highly photoconductive material that is discharged by light photons

Laser printers Initially the drum is given a positive charge by the charge corona wire This is a wire with an electrical current running through it As the drum revolves, the printer shines a tiny laser beam across the surface to discharge the charge at certain points

Laser printers In this way, the laser "draws" the letters and images to be printed as a pattern of electrical charges – an electrostatic image The system can also work with the charges reversed – that is, a positive electrostatic image on a negative background

Laser printers Once the pattern is set, the printer coats the drum with positively charged toner Since it has a positive charge, the toner clings to the negative discharged areas of the drum, but not to the positively charged "background"

Laser printers With the powder pattern on the drum, it rolls over the paper, which is moving along a belt below Before the paper rolls under the drum, it is given a negative charge by the transfer corona wire (charged roller)

Laser printers Because this charge is stronger than the negative charge of the electrostatic image, the paper pulls the toner powder away from the drum Since it is moving at the same speed as the drum, the paper picks up the image pattern exactly

Laser printers To keep the paper from clinging to the drum, it is discharged by the detac corona wire immediately after picking up the toner

Laser printers The printer then passes the paper through the fuser The fuser is a pair of heated rollers As the paper passes through these rollers, the loose toner powder melts, fusing with the fibres in the paper The fuser rolls the paper to the output tray

Laser printers

Laser printers - Advantages Have a high print speed, which makes them very useful in an office environment Are very reliable Have a low print cost per page when printing in black and white Use standard paper Are quiet when operating

Laser printers - Disadvantages Have a high initial start-up cost Use more electrical power than other printers Have a high print cost per page when printing in colour

Dot matrix printers Dot matrix printers were – at one time – very common, but now they are rarely found outside certain specialist business environments They are also know as impact printers because they work by hitting a matrix of small pins against an ink-impregnated ribbon

Dot matrix printers

Dot matrix printers The matrix of pins form the characters, and when the ribbon is pushed against the paper by the impact, the characters are printed

Dot matrix printer head Dot matrix printers Dot matrix printer head

Dot matrix printers - Advantages The dot matrix printer has several unique advantages over other printers including: Their ability to print multi-part forms using NCR (no carbon required) paper; this enables several copies of the same form to be printed so that they can be distributed to different parts of an organisation Their ability to print on continuous stationery – the sprocket feed enables continuous (and often NCR) stationery to be used; this is particularly useful when printing product lists, stock lists, etc.

Dot matrix printers - Advantages Continuous feed paper NCR (no carbon required) forms

Dot matrix printers - Advantages Their reliability because they use simple technology that rarely fails Their ability to switch between different paper sources

Dot matrix printers - Disadvantages The dot matrix printer has several disadvantages: They are very noisy The characters that are printed are unclear because they are a matrix of dots and not a completely formed character They cannot produce graphical images They can only print in the colour of the ribbon that has been installed in the printer

Thermal printers Thermal printers are popular with users who need fast, silent, and high quality output They are used in: Cash registers and point-of-sale terminals Cark park ticket printers Lottery ticket printers

Thermal printers

Multifunctional printers Multifunctional printers (often called PSCs [printer/scanner/copiers]) are very popular in environments (e.g. home offices, small offices) where space or specialist usage are limited

Multifunctional printers They combine several related information communication technologies into one machine: Printer (usually either an ink-jet or laser printer) Scanner Photocopier Fax machine

Multifunctional printers

Selection and use of output methods, media, and devices: Printers AS Level ICT Selection and use of output methods, media, and devices: Printers Unit 1 Topic 6 - 06a - Output devices - Printers