Input Devices

Text Entry Devices, Positioning, Pointing and Drawing

Keyboard

• QWERTY

Keyboards cont…

• Alphabetic keyboard

• Chord keyboard

Mobile Phone Keypad

Handwriting Recognition

• Simple and intuitive

• Slow and a high error rate

The Mouse

• Developed in 1964 by Douglas C. Engelbart

The Mouse

Touchpad

• First introduced by Apple in the Powerbook.

Trackball

Joystick

• Absolute and Isometric

TOUCH SCREEN

A Touch Screen is a touch-sensitive display used to read the position of a fingertip. The screen displays options, which a user can select, simply by

touching them.

Detection of pointing device is made by monitoring infrared beams which ‘ criss cross’ the screen of the conventional monitor just in front of the

glass.

It is particularly suitable for choosing menus in shopping malls, job centres and any other public places where people should find information in a user friendly way and where mice or track balls etc. could easily be stolen or abused.

EYEGAZE

The Eyegaze Communication System is a communication and control system for people with complex physical disabilities. The system is operated entirely with the eyes. By looking at control keys displayed on a screen, a person can synthesize speech, control his environment (lights, appliances, etc.), type, operate a telephone, run computer software, operate a computer mouse, and access the Internet and e-mail. Eyegaze Systems are being used to write books, attend school and enhance the quality of life of people with disabilities all over the world.

As a user sits in front of the Eyegaze monitor, a specialized video camera mounted below the monitor observes one of the user's eyes. Sophisticated image processing software in the Eyegaze System's computer continually analyzes the video image of the eye and determines where the user is looking on the screen. Nothing is attached to the user's head or body.

LIGHT PEN

• This is a device for enabling a person to draw a picture or write on the screen of a computer by use of a special pen which detects light from the screen.

• It has an optical sensor in its tip and can be used in conjunction with a cathode ray tube (CRT) display, which creates images on screen through the use of scanning electron beam.

• It may also be used in conjunction with a drawing package to create, edit or manipulate images on screen.

• LCD (liquid crystal display) displays used in laptops, notebook and palmtop computers do not make use of electron beam scanning and cannot, therefore support the use of light pens.

DIGITISING TABLET

• A graphics tablet is a computer peripheral device that allows one to hand-draw images directly into a computer, generally through an imaging program . Graphics tablets consist of a flat surface upon which the user may "draw" an image using an attached stylus, a pen-like drawing apparatus. The image generally does not appear on the tablet itself but, rather, is displayed on the computer monitor.

• A graphics drawing tablet used for sketching new images or tracing old ones. The user makes contact with the tablet with a pen or puck (mistakenly called a mouse) that is either wireless or connected to the tablet by a wire. For sketching, the user draws with the pen or puck and the screen cursor "draws" a corresponding image.

• When drawing or tracing on the tablet, a series of x-y coordinates (vector graphics) are created, either as a continuous stream of coordinates, or as end points.

The End