Input Devices

Input Devices

1. Keyboard

   • Arrangement of keys that contain characters and other functions that operate a computer
     • different arrangements of keys are available
   • switches and circuits are used to translate a person's keystrokes into a signal a computer can understand
     • Mechanical
       • When the user presses a key, a circuit is completed and signals are sent to the processor
     • Capactive
       • When a key is pressed, a tiny plate moves closer to another plate beneath it. This causes a change in the amount of current flowing, which is detected by the processor
   • Different types of keyboards available.
     • Ergonomic
     • Concept keyboard
     • Brail
     • Gaming
     • Virtual

2. Optical Mouse

   • Uses an LED to bounce light off of a surface. which is reflected back onto a sensor
     • Sensor identifies patterns in images captured and observes how the patterns change.,
   • Benefits
     • No moving parts; more durable
     • Increased resolution; more precise
     • A special surface, such as a mouse pad, is not required.

3. Trackball

   • Consists of a ball, held by a socket
     • Connected to sensors which detect rotation of the ball about 2 axes

4. Joystick

   • Takes something entirely physical - movement of the hand - and converts it to something entirely mathematical - a binary string
   • A circuit board is present beneath the stick
     • Printed wires carry electrical signals between contact points
   • Several different joysticks can recognize movements in several different directions

5. Barcode Scanner

   • A red laser is shone onto a barcode
     • The white parts of the barcode reflect more light than the darker parts, allowing a pattern to be identified.

6. Scanner

   • 2-D
     • A light illuminates the document, which is then converted into a digital image.
   • 3-D
     • Scans object in x,, y and z axes.

7. Sensors

   • Light
   • Pressure
   • Motion
   • Infra-red
   • ph
   • Sound