INPUT DEVICE

INPUT DEVICES

An input device is an electromechanical device that accepts data from outside world and translates them into a form a computer can interpret. Several input devices are available today. we classify them broadlly into following categories:

1. Keyboard                                      2. Point-and-draw devices

3.Data scanning devices                   4. Digitizer

5. Electronic cards based devices     6.Speech recognition devices

7. Vision based devices

1. Keyboard

Keyboard device are the most commonly used input device today. They allow data entry into a computer system by pressing a set of keys(labeled buttons) neatly mounted on a keyboard connected to a computer system. The most popular keyboard used today is the 101 -keys QWERTY keyboard.

2. Point-and-Draw-Devices

The point and draw device is an input system that helps to point and select an icon to be shown on the screen quickly. Some of the most common point and draw devices are. Trackball, Mouse, Joystick, Explanation.

3. Data scanning Devices

Data scanning devices are input devices that allows data entry from source documents directly

Some of them are also capable of recognizing marks or characters. These devices have follow-

ing characteristics:

1. They eliminate the need for manual entry of data by human beings, thus, improving data accuracy

and timeliness of the data processed.

2. Automatic entry of data with their use improves data accuracy and increases timeliness of the 

information processed.

3. They demand high quality of source documents because of direct data entry. Normally, they 

reject documents typed poorly, having strikeovers, or having erasures.

4, Form design and ink specification requirements become more critical with the use of these 

devices than with the use of keyboard devices for data entry.

4. Digitizer

A  digitizer is an input device used for converting (digitizing) pictures,maps and drawings into digital form for input to computers. For example, x and y coordinates of points in a line drawings may be stored in digital form. This enables re-creation of the drawing from the stored information and easy incorporation of changes in the drawings, whenever required.

5.Vision input system

A vision input system allows a computer to accept input by seeing an object. Input data is this case is normally an object's shape and fetures in the form of an image. The idea is to simulate the capability of a human vision system in a limited sense.

A computer with a vision input device consists of a digital camera and follows the followig steps to recognize a given object:

1. It focuses the camera on the given object to take its picture.

2. The camera creates a digital images of the object and feeds it to the computer.

3. The computer matches the image with similarly formed pre-store images in its image database.

4. The computer takes appropriate action depending on whether it finds a match or not