Lecture Thirteen Printer Technology

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Lecture ThirteenPrinter Technology
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The Technologies

• Dot matrix
• Inkjet
• Solid ink
• Laser
• Colour laser
• Thermal wax transfer
• Dye sublimation

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Dot Matrix

• Old technology - rarely used today
• Print-head consists of a column of 7 to 24 pins
• Selected pins strike the paper througha ribbon
• Limited colour possible by usingmulti-colour
  ribbon
• Problems with alignment of columns
• Relatively slow, every copy takes same time

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Inkjet

• Sprays a stream of CMYK ink through a set of fine
  nozzles mounted in a disposable cartridge.
• Heat sometimes applied to aid the inks drying.
• Ink tends to bleed into ordinary paper.
• Special paper often used - adds to the expense.
• Resolutions of up to 1440dpi possible.
• Capital cost low, running costs high.
• Solid ink variations are now on the market.

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Laser

• Xerographic process
• Charge transfer
• Image on drum by laser
• Toner
• Heat to fix image
• Resolutions up to 1200dpi possible
• Higher capital cost, lower running cost

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Laser / Colour laser

• Colour possible by having 4 such mechanisms

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Thermal Wax Transfer

• Roll of plastic film coated with
  pigment-impregnated wax
• Roll alternates page-sized panels of CMYK
• Print head has thousands of heating elements
  which melt the wax and transfer it to the paper
• Glossy appearance to prints vivid colours
• Excellent results for OHP transparencies
• Fixed running cost per sheet

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Dye Sublimation

• Similar to thermal wax transfer - CMYK roll
• Differs in method of colour transfer to paper
• inks are opaque and make a solid dot
• dyes are transparent and merely tint the print
  media
• (varied) heat changes the solid dye directly into
  a gas
• immediate absorption by the polyester coating of
  the print medium, producing a small coloured dot
• dyes can mix, so no dithering is required
• photographic quality results