Printers

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Printers

• a users perspective

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There are two major types

• Laser
• Inkjet (or bubble-jet)

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Technobabble
Laser Printers are peripherals that use a series
of mirrors and lenses to "apply" the text or
image onto an internal revolving drum. This
application is accomplished by changing the
electrical polarity of the drum's surface in the
appropriate places. Toner, which is electrically
charged with the opposite polarity of the image
on the drum, is then applied to the drum and
adheres in the designated pattern. Paper heated
to a precise temperature is then sent past the
drum, which applies the toner to the page.
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Lasers

• From the users point of view, the result is
  generally a 600 dots per inch image
• It is cheap and consequently ideal for high
  volume environments.
• The initial outlay is high but cost per page is
  around 2 cents as opposed to 23 cents for
  inkjets.
• The break-even point for black and white is
  around ten pages per week.

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Lasers

• Colour lasers require four sets of everything
  drums, rollers and toner.
• Most lasers for the cheaper (home use) can only
  be refilled up to (usually) about four times.
• Replacement rollers, drums, etc can cost around
  250, making 1,000 total, thus making a new
  printer a viable option.

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Lasers

• Colour laser printers are not generally
  considered viable for the home user because
• The colour tends to be bright like an
  advertisement
• The long-term cost makes ink-jets more viable.
• They cannot print on coated papers.

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Lasers

• The hot paper requirement of lasers has been
  utilised in an interesting way
• Coloured plastic sheets can be placed on a
  previously printed page and fed back through the
  printer.
• The black text picks up more heat that the white
  paper. The plastic melts on to the black text but
  not the paper, giving interesting patterns
  (metallic gold, etc).

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Ink Printers

• Ink-jet printers. When a quartz crystal is
  squeezed, it produces an electrical current. When
  a currant is applied, it distorts. This
  characteristic is used to force the ink out.
• Bubble-jet printers. The ink is heated to a
  vapour and thus forced out of the nozzle.
• From the USERS point of view there is therefore
  no difference.

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Technobabble

• In bubblejets, the ink is heated to over 600oC.
• It leaves the print-head at about 500 inches per
  second.
• No wonder it splashes if it hits the wrong
  surface.

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Ink Printers

• The Resolution of your printer depends on
• The number and spacing of holes in the print head
  (around 1,120)
• The size of the holes
• The speed of the paper past the head
• The type of ink used
• The type of paper
• Photocopy papers absorb the ink, wick it
  feather it or let it flow into microscopic
  crevasses.

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Types of printer ink

• Water-based Until recently this was the most
  usual but the ink tends to feather or bleed and
  is unsuitable for the high resolutions required
  in todays market.

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Types of printer ink

• Oil based The droplets can be formed using very
  small quantities of ink, so it is suitable for
  high resolution printers.
• Expensive.
• Can clog, especially if the printer is not used
  for a few days.

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Types of printer ink

• P-POP. A coagulant is incorporated in with the
  black reservoir. This is sprayed on to the paper
  before the ink, so coated papers are not
  required. The idea does not appear to have caught
  on and is being phased out.

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Types of printer ink

• Phase-change inks. These are solid at room
  temperature and heated before ejection
• No feathering. However, these are unsuitable for
  home use since they need to be run at high
  volume.

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Print it

• For best quality, print at twice the graphic
  resolution only
• Use coated paper gloss, semi matt or matt
  this prevents bleeding
• There is no white ink, so use the whitest and
  brightest paper you can get.
• Quality counts use the best inks, the best
  paper and the best printer you can afford.

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Micrograph of ink at 1440 on copier paper
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on 1440 matt paper
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on 1440 glossy
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on HP2000 matt photo paper
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Special Papers

• There are a wide variety of specialty papers
  available
• Pre-printed for labels, certificates, parties,
  formal occasions, etc.
• Coloured, stippled and pre-cut giving the effect
  of parchment, papyrus, hand-made, cloth, etc.
• One allows the high-speed ink to permeate the
  gloss surface, giving it a water-proof finish.

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Colour Gamut
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(No Transcript)
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Buying a Printer

• Print-head built in this is the ideal type
  because the holes can be machined to a greater
  accuracy. However, if the printer is left for
  more than a week it can clog and it takes an
  expert to clean.

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Buying a Printer

• Print-head part of the ink reservoir. These are
  mass produced and can vary slightly. However, if
  the head clogs, it is a simple matter to clean or
  replace the cartridge.

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Buying a Printer

• Reproduction. The colour will vary between
  manufacturers and between machines.
• The more colours used, the better the output
  (usually).

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Buying a Printer

• Always take a disk with a photograph on it in to
  the shop and ask them to print it for you.
  Compare it with a print you like.
• Look for skin tones and reproduction of fine
  lines (hair, etc).
• Look for artifacts spots and marks that are not
  on the original.

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Buying a Printer

• Resolution. Generally, the higher the resolution,
  the slower the print and the more expensive the
  machine and the cartridges.
• As the resoloution increases, the number of holes
  increases and their size decreases.
• This increases the chance of ink blockage.

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Buying a Printer

• An ink printer should be used every day or the
  ink may dry on the head causing blockage.
• Some printers incorporate the print-head with the
  reservoir, thereby increasing the cost. However,
  for home use this is ideal because if the ink
  dries or blocks, it is a simple matter to replace
  the cartridge.

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Buying a Printer

• Others incorporate it with the printer itself.
• This saves on replacement cartridge costs and
  gives a more accurate print head. However,
  cleaning a blocked head becomes time consuming
  and expensive.
• Ideally, this type of printer should be used
  every day and never left idle over holidays, etc.