1. 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 a - Output devices - Printers

2. 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 a - Output devices - Printers

3. 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 a - Output devices - Printers

4. 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 a - Output devices - Printers

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

6. 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

7. 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

8. 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

9. Ink-jet printers
Print head
Stepper motor

10. 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

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

12. 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

13. Ink-jet printers
Rollers

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

15. 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

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

17. Laser printers

18. 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

19. 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

20. 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

21. 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

22. 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"

23. 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)

24. 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

25. 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

26. 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

27. Laser printers

28. 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

29. 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

30. 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

31. Dot matrix printers

32. 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

33. Dot matrix printer head
Dot matrix printers
Dot matrix printer head

34. 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.

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

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

37. 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

38. 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

39. Thermal printers

40. 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

41. 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

42. Multifunctional printers

43. 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 a - Output devices - Printers