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Typical uses of a joystick include video games, flight simulators, training simulators, and
for controlling industrial robots.
Another point-and-draw device is an electronic pen. In a pen-based system, you hold the
pen in your hand and directly point with it on the screen to select menu items or icons; or
directly draw graphics on the screen with it; or write with it on a special pad for direct
input of the written information to the system. Electronic pens are of the following types:
1. Light Pen. It uses a photoelectric (light sensitive) cell and an optical lens mounted in
a pen-shaped case. The photoelectric cell and lens assembly is designed in such a way
that it focuses onto it any light in its field of view. Hence with this mechanism the pen
can be used to indicate screen position to the computer. You operate the pen by moving
its tip over the screen surface. As the light pen is moved over the screen surface, it detects
the light being emitted from a limited field of view of the monitor's display. This electric response is transmitted to a processor, which can identify the menu item or icon that is
triggering the photocell. In this manner, the graphics cursor automatically locks on to the
position of the pen and tracks its movement over the screen. The case of the pen has a
finger-operated button, which is used to select an option from the screen by clicking it.
In addition to being used for pointing and selecting options from a set of options
displayed on the screen, light pens are frequently used for computer-aided design (CAD)
applications. For example, the user can directly draw on the screen with a light pen. By
using the pen along with a keyboard, the CAD application can allow users to select
different colors and line thicknesses, reduce or enlarge drawings, and add or erase
graphics objects such as lines, circles, rectangles, etc.
Writing Pen with Pad. This type of electronic pen comes with a special type of
writing pad. The pen is used to write on the pad whatever information the user wants to
input to the computer system. Although this input device may app...
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This document was uploaded on 04/07/2014.
- Spring '14