Types of Computer Input Device

The input unit is formed by the input deceives attached to the computer. These input devices take input in different forms from the user and convert it into machine understandable form. Some commonly used input devices are the keyboard, mouse, scanner, joystick, trackball, touch pad, touch screens, light pen and bar code reader.

Some of these input devices are discussed below:

Keyboard:
The keyboard is used to feed letters, numbers and commands into the computer. Most keyboards have between 80 and 110 keys, including: Typing keys, Numeric keypad, Function keys and Control keys.
The typing keys include the letters of the alphabet, generally laid out in the same pattern used for typewriters. As you press an alphabet/number key on the keyboard meth character appears on the computer screen where the cursor is positioned. As you type, the cursor keeps moving accordingly.
The keyboard helps you to work faster. You have learnt about some keyboard commands in the previous class.

Mouse:
The mouse is used to move the cursor or open a file or folder. The main goal of any mouse is to translate the motion of our hand into signals that the computer can use. These are a ball inside the mouse which touches the desktop and rolls when the mouse moves.

Scanner:
A scanner is an input device that copies written documents, photographs and pictures and transfers them to the computer directly. It scans the image and converts it into a computer acceptable format.
The scanner shines a bright light on the photograph or image to be scanned, which is reflected back by the image. The scanner senses the intensity of this reflection at every point and converts the image into a code that can be understood by the computer.
The two most common types of scanners are the handheld and the flatbed scanners.

Joystick:
A joystick is a pointing device that functions like a mouse. It is mostly used in computer games. It has a rotary lever that can be moved right, left, backward or forward. A joystick helps you to move an image quickly across the screen, and hence, is used for playing computer games, in training stimulatory and in controlling robots.
Touch screens:
The touchpad is a pressure sensitive input device that responds to your finger movements over the pad’s surface. It is usually found on laptop computer.

Trackball:
A trackball is like an upside down mouse in which you roll the ball directly with your hand to control the pointer on the screen. It is mostly used in laptop computers. These days, some computer mice also have a separate trackball, along with the buttons, for easier scrolling.

Touch Screens:
A touch screen allows you to feed in data by simply touching the screen the user selects options from the menu displayed on the screen. The computer senses the instructions and functions accordingly. A touch screen uses a transparent pressure sensitive panel to detect where the user has tapped the screen. Touch screen are usually seen in kiosks: kiosks are the booths that provide computer service of some types. Touch screens are also seen in ATMs, supermarkets.

Light Pen:
This is a pointing device that resembles a pen. You can select options on the display screen by simply moving the pen pointer over them. You can also draw figures on the screen by moving the light pen over the screen.
The tip of the light pen has a light sensitive detector. When the tip is in contact with the screen, it detects the light from the screen. The computer then identifies the location of the pen on the screen and works accordingly.

Bar Code Reader:
You will find a pattern or printed bars on various products in the market. Even your library books will have a similar pattern on the back cover. This pattern is known as a bar code. To read this code, you need a Bar code reader which decodes and transfers it to the computer system where it is processed.