TOUCH SCREEN TECHNOLOGY

Subrat kumar MoharanaRegd. No:-0711016018ENTC-A

TALK FLOW INTRODUCTION HISTORY FUNCTIONS WORKING TOUCH SCREEN TECHNOLOGY APPLICATION CONCLUSION

INTRODUCTIONA touch screen is a computer display screen

that is sensitive to human touch, allowing a user to interact with the computer by touching pictures or words on the screen.

A touch screen is an input device that allows users to operate a PC by simply touching the display screen which has a sensitive glass overlay placed on it .

A touch screen accepts direct onscreen inputs.

HISTORY In 1971, the first "touch sensor" was

developed by Doctor Sam Hurst (founder of Elographics) while he was an instructor at the University of Kentucky.

The University of Kentucky Research Foundation named it as “Elograph”.

The "Elograph" was not transparent like modern touch screens.

In 1974, the first true touch screen incorporating a transparent surface came.

HOW DOES A TOUCHSCREEN WORK?

A basic touch screen has three main components:

touch sensor controller software driver

1.TOUCH SENSOR A touch screen sensor is a clear glass panel

with a touch responsive surface which is placed over a display screen.

The sensor generally has an electrical current or signal going through it and touching the screen causes a voltage or signal change. This voltage change is used to determine the location of the touch to the screen.

2.CONTROLLER The controller is a small

PC card that connects between the touch sensor and the PC.

It takes information from the touch sensor and translates it into information that PC can understand.

3.SOFTWARE DRIVER The driver is a software that allows the touch

screen and computer to work together. It tells the operating system how to interpret

the touch event information that is sent from the controller.

Most touch screen drivers today are mouse-emulation type drivers. This makes touching the screen the same as clicking your mouse at the same location on the screen.

DIFFERENT TOUCH SCREEN TECHNOLOGIES

RESISTIVE CAPACITIVE SURFACE WAVE INFRARED DISPERSIVE SIGNAL

TECHNOLOGY

RESISTIVE TOUCH SCREEN TECHNOLOGY

1. Polyester Film .2. Top Resistive Layer.3. Conductive Transparent Metal Coating.4. Bottom Resistive Layer .5. Insulating Dots .6. Glass Substrate

Contd.

Pressing the flexible top sheet creates electrical contact with the coating on the glass.

The touch screen controller gets the alternating voltages between the two layers and converts them into the digital X and Y coordinates of the activated area.

Working of touch screen in an integrated circuit

In case of measurement of X coordinate ,the top sheet caries a voltage gradient generated by applying a voltage between the electrodes of top sheet .the bottom sheet serve as a slider in a linear potentiometer .The X co-ordinate is estimated considering the equivalent resistance between the touch point to each linear electrode in top sheet.

Internal Structure

Implementation

X1=k(Vrtl+Vrtr+Voffset) X2=k(Vrtl+Voffset)

X3=k Voffset

The x-coordinate is calaulated from: X=(X2-X3)/(X1-X3)

similarly; Y=(Y2-Y1)/(Y1-Y3)

Equivalent Resistance

Block diagram

Advantages of Resistive Technology

Can be activated with any device Low cost solution Low power consumption

Disadvantages of Resistive Technology

Poor durability Lower resolution Less Accuracy

APPLICATIONS Public Information Displays tourism displays, trade show displays

Customer Self-Service stores, restaurants, transportation hubs, ATM and airline e-ticket terminals.

And many more uses... computerized gaming, student registration systems, multimedia software, financial and scientific applications, and more.

CONCLUSION Touchscreens, touch panels or touchscreen

panels are display overlays which have the ability to display and receive information on the same screen.

Touchscreens also have assisted in recent changes in the PDAs, making these devices more usable.

REFERENCES [ 11 Sandbach, David Lee: Position detector constructed from fabric, European patent EP 0989509A2 [2] Microtouch Systems, Inc.: Frontally Shielded Capacitive touch sensor system, United States Patent US5457289 [3] Summagraphics Corporation: Method and apparatus for calibration of a charge

ratio digitizer, United States Patent US483 1566 [4] Microtouch Systems, Inc.: Touchscreen controller with pen andor finger inputs,

United States Patent US5457289 [5] Peptek, Incorporated: Touch panel system and Method, United states Patent

US4353552