Touch Screen Computer Technology

Touch Screen
Imagine a cardiac surgeon performing an intricate bypass surgery. In between, the surgeon needs to check the laboratory test results of the patient. Assuming that the information is stored on a computer, the surgeon can access the information through a keyboard, or better still, through a mouse. But how much more convenient would it be if the surgeon could only touch the screen on the option that is required to display the information. A touch screen input interface does exactly this. Touch screens are normally used when information has to be accessed with minimum effort.

Touch screens are used in information-providing systems like the one explained above. It is also used in airline and railway reservation counters. The users indicate their current location and the destination by touching the screen (maybe on a map), and all the possible routes with timings and rates are displayed. These interfaces are also used in travel agencies to display the names and address of all hotels, restaurants, and other places of interest, at a desired destination. Touch screens are also used in stock exchanges.

There are four types of touch screens. They are:
Resistive touch screens:The resistive touch screens is made sensitive to touch and the exact position is detected. This technology is recommended for use in Point of Sale, such as Hotels, Restaurants and Retail Stores. This type of touch screens is generally the most affordable.
Infrared touch screens: The infrared touch screen is lined with light emitting devices and photo-detectors. When the user's finger approaches the screens, the light beam is broken and is detected by the photo-detectors. The drawback with this technology is that your screen may sometimes react you physically touch it.

Surface Acoustic touch screens: The surface acoustic wave technology is one of the most advanced touch screen. These screens send sound waves across your screen surface to look for interruptions caused by touch. Mostly it is used for public information kiosks; computer based training, or other high traffic indoor environments.

Capacitive touch screens: The capacitive touch screen is coated with a material that stores electrical charges. When the screen is touched, the charge is drawn to the point of contact. This charge is detected and measured by the circuits located at each corner of the screen. The circuits send the information to the controller for processing. Grease, water and dirt do not affect capacitive touch screens.
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Light Pen

Light Pen







A light pen is a pointing device that can be used to select an option by simply pointing at it, or to draw figures directly on the screen.

A light pen has photo-detector at its tip. This detector can detect changes in brightness of the screen. When the pen is pointed at a particular spot on the screen, it records change in brightness instantly and informs the computer about this. The computer can find out the exact spot with this information. Thus. the computer can identify where you are pointing on the screen.

Light pens are useful for drawing graphics in programs, such as Computer Aided Design(CAD). An engineer, architect or a fashion designer can draw directly on the screen with the pen. Using a keyboard and light pen, the designer can select colours and line thickness, reduce or enlarge drawings, and edit drawings.

Scanner Input Device And Saveral Kinds Of Scanner

Another input device that is being used increasingly is the scanner. Often, there are situations when some information (picture or text) is a available on paper and is needed on the computer disk for further editing. The simplest way to do this would be to take photograph of the image directly from the source, and convert it into a form that can be saved on the disk and then edited.

A scanner scans an image and transforms the image to ASCII codes that is used by the computer to represent the characters you find on you keyboard, such as, alphabets, numbers, punctuation marks and graphics. These can be edited, manipulated and printed.

There are three types of scanners:

Flatbed Scanner: The Flatbed scanner is most common desktop scanner. It resembles the copy machine. In a Flatbed scanner, The item being scanned rests on a glass plate whicle the scanning head moves underneath it. It works like a copy machine except that it creates a file of the document rather than a paper copy.
Sheetfed Scanner: Personal sheetfed scanners have gained popylarity during the last few years. These devices are more like fax machines, because they move the page being scanned past the scanning head. The main difference between this type and a flatbed scanner is that the image sensor does not move but the document itself is pulled past the mounted image sensor.
Handheld Scanner: The handheld scanner is a scanning device where the scanning element is built inro a small handheld unit. The handheld unit is then waved or rolled over the item being scanned.

Many of the scanners available now-a-days are capable of not only scanning text and graphics, but also integrating text and graphics files.

Scanners are used to reproduce photographs on the computer screen. They can be used in training programs using computes and in desktop publishing. Businessses use scanners for storing documents on the computer.

Comouter Input Devices Mouse

myLot User ProfileThe mouse was invented by Douglas Engelbart of Stanford Research Center in 1963, and pioneered by Xerox in the 1970s.

The mouse is an input device that is important for graphical user interfaces because you can simply point to option and click a mouse button. These types of applications are often called point-and-click programs. The mouse is also important for graphic programs that allow you to draw pictures by using the mouse.

A mouse may have one, two or three buttons. The function of each button is determined by the program that uses the mouse. A software package may use one, two or all there of them. In its simplest form, a mouse has one button. Moving the mouse on a flat surfaces a corresponding movement of a pointer on the screen. Placing the pointer on an option and clicking the button results in selecting that Option.

A mouse may be classified as a mechanical mouse or an optical mouse, on the basis of the technology it uses. In a mechanical mouse, the ball that projects through the bottom surface rotates as the mouse is moved along a flat surface. The direction of rotation is detected and relayed to the computer by the switches inside the mouse. Microsoft, IBM and Logitech are some well-known makers of mechanical mouse.

An Optical mouse uses a light beam instead of a rotating ball to detect movement across a specially patterned mouse pad. MSC Corporation makes the optical mouse that uses LEDs and photo-detectors to trap movement.
Following are some categories of mouse:

Trackball Mouse :- In a Trackball mouse, the ball is rolled at one place with the thumb, fingers and palms rather than rolling the mouse on the table top.

Joystick Mouse : A Joystick usually includes two upright sticks that are moved with the hand a button is pressed on either stick. Joystick mouse is basically used by children, recreational users and other who prefer the joystick to the mouse or trackball.


Light Pen Mouse : A light pen utilizes a light-sensitive detector. It requires you to hold a pen and point it at the screen.

Wireless Mouse : The wireless mouse is a mouse without a cable. This mouse works upto one and a half metres away from the computer.
Touch Pad Mouse : A touch pad is a small, flat, rectangular pointing device that is sensitive to pressure and motion. These devices are mostly used on portable computers.