Printers Types commonly used with microcomputers Laser printer Uses a technology similar to that

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Printers Types commonly used with microcomputers Laser printer Uses a technology similar to that Powered By Docstoc
        Output Devices
        Is any hardware component that
         conveys information to one or more

        Two Types
           Hard Copy ---- also called printout
           Soft Copy

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                               Hard Copy
              is an output device that produces text and graphics on a
              physical medium such paper or transparency film.

           Are sophisticated printers used to produce high-quality
              drawings such as blueprint, maps, and circuit diagrams.

           film on which materials are photographed at greatly
            reduced size; useful for storage; a magnification system is
              used to read the material

           small sheet of microfilm on which many pages of material have
            been photographed; a magnification system is used to read the
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        Other output devices
                       Soft Copy

         screen :
         speaker and headset
         another computer

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                        Types of printers

         Impact printers
           Daisy wheel, band, chain and drum printers (old
            technology )
           Dot Matrix printer
           line printer
         Non-impact printers
             laser
             ink jet
             thermal
             photo

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   • Types commonly used with
        – Laser printer
           • Uses a technology similar to that used in a
             photocopying machine
           • High quality
        – Ink-jet printer
           • Sprays small droplets of ink at high speed onto the
             surface of the paper
           • inexpensive
        – Thermal printer
           • Uses heat elements to produce images on heat-
             sensitive paper
           • Very high-quality color artwork

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Laser printer             Ink-jet printer

        Thermal printer

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        Photo Printer

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  • Dot-matrix printers
        – Using a series of small pins on a print head
        – Inexpensive
        – Noisy, quality not high

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         Also called VDU, terminal, monitor etc
         Types of screens:
           cathode ray tube (CRT): Most common screen
               is a desktop monitor that is similar to a standard television
                because it contains a cathode-ray tube.
           liquid crystal display (LCD)
               Also called flat panel monitor, is a desktop monitor that uses a
                liquid crystal display instead of a cathode-ray tube to produce
                images on a screen.  sharp , flicker-free displays
           Gas Plasma
               Uses gas plasma technology which substitutes a layer of gas
                for the liquid crystal material in a flat panel monitor.

         Pixel:
         Resolution
         Monitor Standards
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         pixel :
           Each spot is called a pixel , short for picture
            element, is the smallest element in an
            electronic image.
           The colour of each pixel is stored in the
            graphics card as a number:
             256 colours = 8bits(1 byte) per pixel
             16 colours = 4 bits per pixel
         Resolution
          Describe the sharpness and clearness of an
           image, usually defined in pixels.
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                     Other output devices

         Fax
          – Send and receive images over telephone

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           Data projectors
 Is a device that takes the image from a
  computer screen and projects it onto a large
  screen so an audience of people can see the
  image clearly.

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• Microfiche

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• Plotter
            Plotter in 1984

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                     Voice Output
• Produce sounds for people
• Widely used devices
        – Speakers & Headphones
        – Connected with sound card
           • Capture and play back recorded sounds
        – Music player: MP3
• Voice output is common and simpler than
  voice recognition
        – Soft-drink machines, telephones, cars, language
          learning, supermarkets checkout counter, assist
          the physically challenged
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        sound card

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         The most commonly used
  • Cathode-ray tubes(CRT)
        – Similar to televisions
        – Low cost and excellent resolution
        – Size big, with radialization

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          The most commonly used
• Flat-panel monitors
        – Also called liquid crystal display(LCD)
        – Much thinner than CRTs
        – 2 types of flat-panel monitors
          • Passive-matrix
             – Scanning entire screen
             – Need little power, not very clear
          • Active-matrix(thin film transistor,TFT)
             – Each pixel is independently activated
             – Require more power, more expensive, better clarity
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        Gas Plasma

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             Monitor Standards
  • Indicate screen quality
  • Most common standards
        – SVGA: Super Video Graphics Array
          • 800X600, for 15-inch monitors
        – XGA: stands for Extended Graphics Array
          • 1024X768, for 17- and 19-inch monitors
        – SXGA: stands for Super Extended Graphics
          • 1280X1024, 19- and 21-inch monitors
        – UXGA: stands for Ultra Extended Graphics
          • High-end engineering design and graphic arts
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