Keyboard is the essential part of the computer used for the direct human input to the computer. It is a typewriter style device in which the buttons act as electronic switches to provide input to the computer. The common keyboard is the Alphanumeric keyboard with a combination of Alphabetic and Numeric keys. The keys in the keyboard correspond to written symbols, but to produce specific actions, combinations key stroke is necessary. Keyboard produces input for numbers, letters, signs etc. Some keys in the keyboard produce action or function commands. Normally the keyboard is used to type text and numbers in word processor or similar programmes and the interpretation of the keystroke is left to the software. The keystroke is identified by the software in the computer and expresses the data in visible form or as commands. The combination of Ctrl – Alt – Del keystroke opens the windows task manager to close a programme or to shut down the computer. The typical Keyboard consists of numeric keys, Number keys and Character keys and Function keys.
Keyboard keys can also be used to open and command the options. Instead of mouse clicks, a well trained person can use combination of keys to control the commands of the PC. The travel distance of the keyboard depends on its size. Keyboard of Laptops and Notebooks have shorter travel distance and reduced set of keys to minimize the size. They may not have Numeric keys and the functions keys have a different position. The keys of a standard keyboard are:
1. Arithmetic keys – +,-,*, / etc
2. Numeric keys – 0-9
3. Cursor arrow keys
4. Navigation keys such as Home, End, Pgup, Pgdn etc
5. Numlock button for enabling/disabling the Numeric pad
6. Enter key
The keys work similar to the keys of a typewriter to enter the data. Many of the keys produce different symbols when the Modifier key or Shift key is pressed. The Alphabets become Upper case or Capital when the Shift key or Caps lock key is pressed. The Numeric characters become symbols or punctuation when the Shift key is pressed. The Space bar in the keyboard is used to enter the space between the words during typing. Since it is large in size, both the thumbs can be used during typing. The Space bar key also has many functions during computer games.
Switch technology is used in computer keyboard to input the commands to the computer. The keyboard has 80-110 durable switches one for each key. On key pressing, a positive response is generated which can be recognized by the software in the computer.
The Optical keyboard works using LED and Photo sensor combination to detect the actuated key commands. The LED and Light sensors are placed inside the Keyboard. Light to the photo sensor is blocked by the actuated key only and provides the signal .Two beams of light-one horizontal and one vertical- are used in the optical keyboard to determine the actuated keys. New versions of keyboard used a combination of different technologies to reduce the cost and also to provide user friendly facilities.
Ergonomic Keyboard is designed with Ergonomic considerations to reduce muscle strain during operations. The Ergonomic keyboard is usually V shaped to allow both Left and Right hands to work similar to the natural form. The Ergonomic keyboards reduce Muscle strain and diseases like Carpel tunnel syndrome.
Ergonomic Key board