Page 24 - CA 165 ver 1.0 Class 9
P. 24

l    Micro-graphic Plotter: In this type of plotter, the paper or other medium is held on both sides at
                       the edges by pinch wheels which gives back-and-
                       forth  movement  to  the  paper  while  printing.  It
                       does not print over the drum.










                                                          l    Inkjet Plotter: In this type of plotter, jets of ink are used in
                                                               place of ink pens. The paper is placed on a drum and inkjet

                                                               with different colours of ink are mounted on a carriage.
                                                               Inkjet plotter can print multi-coloured large drawings.




                  Monitor

                  Monitor is a standard output device. It is also known as VDU (Visual Display Unit) or Screen. Monitor is
                  used for interactive processing i.e. the user can use the screen to interact with or to give instructions to
                  the system unlike a television.

                  Monitors can be either monochrome or coloured. In monochrome screen (though rarely used) there is
                  only one colour (usually white, green, amber or black). The Monochrome monitor’s display is only in Black
                  and White. In colour screens there can be colour combination of upto 2,56,000 colours on monitor. The
                  screen of the monitor is normally measured diagonally and is available in different sizes like 15”, 17”, 21”,

                  34”, etc. The screen of a VDU is divided into specific character positions.
                  In the graphics colored mode the pictures are displayed by combination of dots. The screen is treated as
                  an array of tiny dots called ‘Pixels’. In the graphics mode there is a resolution of 640 dots across and 480

                  dots vertically on the screen. There are different types of adaptors that support display of graphics. The
                  higher the resolution, i.e., more the number of pixels the better is the quality of picture that is displayed
                  on the screen. DPI (dots per inch) is the unit of measurement of resolution applied to printer, scanner,
                  monitor, etc.

                  Types of Monitor

                       CRT Monitor: CRT computer monitors, also known as Cathode Ray
                  l
                       Tube monitors work using a vacuum tube as a display screen. An
                       electron gun is heated to fire electrons onto a phosphorus coated
                       screen. This causes phosphorus to glow and project an image onto
                       the screen. But these monitors are not used anymore because of
                       high cost and heat produced.








                   22     Touchpad Computer Applications-IX
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